Always add timezone information to parsed datetimes; allow one to specify a default timezone.
Adding arbitrary timezone information to test datetimes.
Adding timezone information to github test.
Merge pull request #119 from coddingtonbear/always_timezones_always

Always add timezone information to parsed datetimes; allow one to specify a default timezone.
Merge remote-tracking branch 'upstream/develop' into bugwarrior_marshalling