100% coverage.  Changed travis.yml to require 100% coverage to pass.

We don't need to keep the 100% coverage requirement, but I do want to test it.
Also removed `functoolz.hashable` because it wasn't being used.
Coverage requirement worked!  Now check failing test.
Another coverage test with intentional failure.
Now test success
Test commands in travis.yml are more clear.
Merge branch 'master' into with_coverage
Merge branch 'master' into with_coverage
Don't require 100% coverage for pypy.
not pypy
Also look for 0 missed lines, not just 100%.
Merge pull request #76 from eriknw/with_coverage

100% coverage - merging per @mrocklin