This commit removes babel/es6 from all source and test files, because it was introducing a lot of overhead and only little gain.
This commit fixes and enables integration tests on Travis.
This commit fixes#153 and #151 along the way.
_Originally this commit should have only removed babel, but without working tests that's a bit too hairy._
_I only realized that half way into removing babel/es6, so things are all over the place now._
Closes#153, Closes#151
