Lint: Remove requirement for .jsx files

Heavily debated here:
airbnb/javascript#985

Author: dijonkitchen

.eslintrc.json

@@ -11,5 +11,8 @@
     },
     "globals": {
       "fetch": false
+    },
+    "rules": {
+      "react/jsx-filename-extension": [1, { "extensions": [".js", ".jsx"] }]
     }
 }