Rename feedback fragment properties.

The new FeedbackMessage class would conflict with the FeedbackMessage
property, thus renaming Feedback* to User*.

As a side effect, also reformatting the file.
Add feedback creating support for ITogglClient.
Add FeedbackMessage class.
Send real feedback from FeedbackFragment.
Handle TimeZoneNotFoundException in DefaultTimeProvider.
Merge pull request #280 from toggl/roosmaa-feedback-sending

Implement actual feedback sending