Add fabric support for code coverage

When running either UI or regular tests specify:

```
coverage=True
```

And a text coverage report will be printed to stdout and a tar called
"coverage.tar.gz" will be downloaded that contains html report.
Migration merge issues
Merge pull request #939 from steventlamb/topic/cleanup_doc_refactor

Topic/cleanup doc refactor
lint
more lint via merge
Merge pull request #934 from ahinz/topic/coverage

Add fabric support for code coverage
Merge pull request #940 from ahinz/fix/migrations

Migration merge issues
Remove unused assignment
Use Bacon.never instead of conditional plugging
Simplify return value and make helper function

Had to commit these together because they were both affected by a similar change.
Move things around
Refactor ui tests to make writing tests faster
Add UI test for plot detail

This test was created in conjunction with fixing an actual bug that was discovered in an earlier iteration of this branch and almost introduced.