test babel7 and babel6 in circleci

Author: michalkvasnicak

circle.yml

@@ -16,5 +16,5 @@ test:
   override:
     - yarn test
     # test with babel 7
-    - yarn add -D babel-cli@^7.0.0-beta.3 babel-core@^7.0.0-beta.3 babel-register@^7.0.0-beta.3 babel-preset-env@^7.0.0-beta.3 @babel/core babel-plugin-transform-object-rest-spread@^7.0.0-beta.3 gulp-babel@7.0.0
-    - yarn test
+    - ./install-babel-7.sh
+    - BABEL_7=1 yarn test