Don't swallow errors from helpers; output them to the chunk
Tests that test errors match substrings instead of testing equality of error messages.

This allows tests that throw different errors in PhantomJS vs a browser to pick a commonality and test on that instead of the exact error message.
Pin NPM@1.4 for Travis
Merge pull request #495 from sethkinast/catch-helper-errors

Catch syntax errors in context and fail gracefully