Update FolderJournal reference to entry __unicode__ method to __str__
Remove DayOne test made obsolete by FolderJournal
Fix FolderJournal path tests for Windows paths
Apply Black linting
c.f. commit 7cbca9f60f
c.f. commit 398283a8db3177b1ae122e5b9d6a9d623cf9106f
[Dayone] Skip failing tests on Travis
Travis sets the timezone to UTC, which causes many tests to fail