[WIP] New watch-spec.js (#844)
[WIP] New watch-spec.js (#844)

* added spec-test for incrementIndex/decrementIndex/clear function

* added first spec-test for watch.js

* fixed spec-test for getCode() function

* update on watch-specs

* minor renaming and a few more tests

* Check that executeWatch was called with right params

nteract/hydrogen,nteract/hydrogen,rgbkrk/hydrogen,xanecs/hydrogen