Use esprima-fb package instead of pointing at github
Fix unit tests

`path.join` is a varargs function and joins all arguments. The `map` call passes
index and full array as further arguments.

Test Plan:
all jasmine tests pass
Merge pull request #3 from zpao/esprima

Use esprima-fb package instead of pointing at github
Add travis config
Merge remote-tracking branch 'kassens/testfix'