Rename markdown mail folder to text

The reason for this rename is because it's actually the wrong name. Both the HTML and text directories can contain Markdown, which will be properly rendered. The markdown directory atm just contains the plain text views of the email message.

Note that I chose the "text" naming and not the "plain text" naming because we already use the "text" naming through the codebase at the moment.

Author: driesvints

src/Illuminate/Mail/Markdown.php

@@ -66,7 +66,7 @@ public function render($view, array $data = [], $inliner = null)
     }
 
     /**
-     * Render the Markdown template into HTML.
+     * Render the Markdown template into text.
      *
      * @param  string  $view
      * @param  array  $data
@@ -77,7 +77,7 @@ public function renderText($view, array $data = [])
         $this->view->flushFinderCache();
 
         $contents = $this->view->replaceNamespace(
-            'mail', $this->markdownComponentPaths()
+            'mail', $this->textComponentPaths()
         )->make($view, $data)->render();
 
         return new HtmlString(
@@ -111,14 +111,14 @@ public function htmlComponentPaths()
     }
 
     /**
-     * Get the Markdown component paths.
+     * Get the text component paths.
      *
      * @return array
      */
-    public function markdownComponentPaths()
+    public function textComponentPaths()
     {
         return array_map(function ($path) {
-            return $path.'/markdown';
+            return $path.'/text';
         }, $this->componentPaths());
     }