Refactor filter commands input parsing unit tests
Test organization default filter
Add unit test for SetCommitStatus command

- Create abstract UnitTestFilteredPullRequestCommand class from which the
  Merge and SetCommitStatus unit tests classes inherit
- Add statuses tests to SetCommitStatus unit test class
- Add base test to TravisMerge unit test class
Add SetCommitStatus unit tests to travis yml
Refactor TestDeploy unit tests
Add test for token precedence in get_token_or_user()
merge master -D org -I include -E exclude: PR 82 (Add logic to create tag while updating submodules)
merge master -D org -I include -E exclude: PR 87 (Refactor the TestRebase integration test)