Clean up some unused imports. Version increment for PyPI release.

Merge pull request #46 from uclatommy/develop

Fixing: #39 and #45.

Fix travis.

Fix travis.

Travis osx environment now comes with python3

Additional parameters needed for running python 3.7

Add python 3.7 to travis ci tests

Merge pull request #37 from scovetta/patch-1

Add default sentiment (None) to fix #35

Fix formatting

Merge pull request #33 from uclatommy/release-0.4.0

Merge pull request #32 from uclatommy/develop

Version increment.

Merge pull request #31 from uclatommy/issue-#30