Revert "Upgrade babel to enable typescript syntax"

This reverts commit 8b6311e.

Author: vhfmag

.babelrc

@@ -1,5 +1,3 @@
 {
-  "presets": [
-    "@babel/preset-env"
-  ]
+  "presets": ["es2015"]
 }

package.json

@@ -14,14 +14,12 @@
     "test:watch": "npm test -- --watch"
   },
   "devDependencies": {
-    "@babel/cli": "^7.0.0",
-    "@babel/core": "^7.0.0",
-    "@babel/parser": "^7.3.2",
-    "@babel/polyfill": "^7.0.0",
-    "@babel/preset-env": "^7.0.0",
-    "babel-core": "^7.0.0-bridge.0",
-    "babel-eslint": "^9.0.0",
-    "babel-jest": "^23.4.2",
+    "babel-cli": "^6.14.0",
+    "babel-core": "^6.14.0",
+    "babel-eslint": "^7.0.0",
+    "babel-jest": "^20.0.0",
+    "babel-polyfill": "^6.16.0",
+    "babel-preset-es2015": "^6.14.0",
     "babylon": "^6.17.2",
     "coveralls": "^2.11.8",
     "eslint": "^3.12.1",