chore(package): update vue-loader to version 15.8.0

Closes #58

Author: greenkeeper[bot]

package.json

@@ -88,7 +88,7 @@
     "url-loader": "^0.5.8",
     "vue": "^2.5.17",
     "vue-jest": "^3.0.1",
-    "vue-loader": "^13.3.0",
+    "vue-loader": "^15.8.0",
     "vue-server-renderer": "^2.5.17",
     "vue-style-loader": "^3.0.1",
     "vue-template-compiler": "^2.5.17",