Populate "files" section in each exercise config.json (#495)

This track only contains practice exercises.

script (fish):
```
cd exercises/practice
for d in *
    set e (string replace --all -- "-" "_" $d)
    jq --arg s {$e}".sh" --arg t {$e}"_test.sh" '
        .files = {
            "solution": [$s],
            "test": [$t],
            "example": [".meta/example.sh"]
        }
    ' $d/.meta/config.json | sponge $d/.meta/config.json
end
```

Author: glennj

config.json

@@ -16,10 +16,10 @@
   },
   "files": {
     "solution": [
-      "./%{snake_slug}.sh"
+      "%{snake_slug}.sh"
     ],
     "test": [
-      "./%{snake_slug}_test.sh"
+      "%{snake_slug}_test.sh"
     ],
     "example": [
       ".meta/example.sh"

exercises/practice/acronym/.meta/config.json

@@ -2,9 +2,15 @@
   "blurb": "Convert a long phrase to its acronym",
   "authors": [],
   "files": {
-    "solution": [],
-    "test": [],
-    "example": []
+    "solution": [
+      "acronym.sh"
+    ],
+    "test": [
+      "acronym_test.sh"
+    ],
+    "example": [
+      ".meta/example.sh"
+    ]
   },
   "source": "Julien Vanier",
   "source_url": "https://github.com/monkbroc"

exercises/practice/affine-cipher/.meta/config.json

@@ -2,9 +2,15 @@
   "blurb": "Create an implementation of the Affine cipher, an ancient encryption algorithm from the Middle East.",
   "authors": [],
   "files": {
-    "solution": [],
-    "test": [],
-    "example": []
+    "solution": [
+      "affine_cipher.sh"
+    ],
+    "test": [
+      "affine_cipher_test.sh"
+    ],
+    "example": [
+      ".meta/example.sh"
+    ]
   },
   "source": "Wikipedia",
   "source_url": "http://en.wikipedia.org/wiki/Affine_cipher"

exercises/practice/all-your-base/.meta/config.json

@@ -2,8 +2,14 @@
   "blurb": "Convert a number, represented as a sequence of digits in one base, to any other base.",
   "authors": [],
   "files": {
-    "solution": [],
-    "test": [],
-    "example": []
+    "solution": [
+      "all_your_base.sh"
+    ],
+    "test": [
+      "all_your_base_test.sh"
+    ],
+    "example": [
+      ".meta/example.sh"
+    ]
   }
 }

exercises/practice/allergies/.meta/config.json

@@ -2,9 +2,15 @@
   "blurb": "Given a person's allergy score, determine whether or not they're allergic to a given item, and their full list of allergies.",
   "authors": [],
   "files": {
-    "solution": [],
-    "test": [],
-    "example": []
+    "solution": [
+      "allergies.sh"
+    ],
+    "test": [
+      "allergies_test.sh"
+    ],
+    "example": [
+      ".meta/example.sh"
+    ]
   },
   "source": "Jumpstart Lab Warm-up",
   "source_url": "http://jumpstartlab.com"

exercises/practice/anagram/.meta/config.json

@@ -2,9 +2,15 @@
   "blurb": "Given a word and a list of possible anagrams, select the correct sublist.",
   "authors": [],
   "files": {
-    "solution": [],
-    "test": [],
-    "example": []
+    "solution": [
+      "anagram.sh"
+    ],
+    "test": [
+      "anagram_test.sh"
+    ],
+    "example": [
+      ".meta/example.sh"
+    ]
   },
   "source": "Inspired by the Extreme Startup game",
   "source_url": "https://github.com/rchatley/extreme_startup"

exercises/practice/armstrong-numbers/.meta/config.json

@@ -2,9 +2,15 @@
   "blurb": "Determine if a number is an Armstrong number",
   "authors": [],
   "files": {
-    "solution": [],
-    "test": [],
-    "example": []
+    "solution": [
+      "armstrong_numbers.sh"
+    ],
+    "test": [
+      "armstrong_numbers_test.sh"
+    ],
+    "example": [
+      ".meta/example.sh"
+    ]
   },
   "source": "Wikipedia",
   "source_url": "https://en.wikipedia.org/wiki/Narcissistic_number"

exercises/practice/atbash-cipher/.meta/config.json

@@ -2,9 +2,15 @@
   "blurb": "Create an implementation of the atbash cipher, an ancient encryption system created in the Middle East.",
   "authors": [],
   "files": {
-    "solution": [],
-    "test": [],
-    "example": []
+    "solution": [
+      "atbash_cipher.sh"
+    ],
+    "test": [
+      "atbash_cipher_test.sh"
+    ],
+    "example": [
+      ".meta/example.sh"
+    ]
   },
   "source": "Wikipedia",
   "source_url": "http://en.wikipedia.org/wiki/Atbash"

exercises/practice/beer-song/.meta/config.json

@@ -2,9 +2,15 @@
   "blurb": "Produce the lyrics to that beloved classic, that field-trip favorite: 99 Bottles of Beer on the Wall.",
   "authors": [],
   "files": {
-    "solution": [],
-    "test": [],
-    "example": []
+    "solution": [
+      "beer_song.sh"
+    ],
+    "test": [
+      "beer_song_test.sh"
+    ],
+    "example": [
+      ".meta/example.sh"
+    ]
   },
   "source": "Learn to Program by Chris Pine",
   "source_url": "http://pine.fm/LearnToProgram/?Chapter=06"

exercises/practice/binary-search/.meta/config.json

@@ -2,9 +2,15 @@
   "blurb": "Implement a binary search algorithm.",
   "authors": [],
   "files": {
-    "solution": [],
-    "test": [],
-    "example": []
+    "solution": [
+      "binary_search.sh"
+    ],
+    "test": [
+      "binary_search_test.sh"
+    ],
+    "example": [
+      ".meta/example.sh"
+    ]
   },
   "source": "Wikipedia",
   "source_url": "http://en.wikipedia.org/wiki/Binary_search_algorithm"