Switch back to packaged version of coveralls.

The latest release includes the fix for Unicode decoding, plus it
provides a wheel (which might be faster?).
Run coveralls from the top-level directory.

This should allow coveralls to correctly strip the absolute path into a
relative one. Hopefully that means the reverse links back to GitHub will
work again.
Combine coverage to produce canonical paths.

I hope this gets coveralls to understand things...
Don't skip coverage testing on scripts.
Merge pull request #839 from QuLogic/coveralls-update

Switch back to packaged version of coveralls.