Merge pull request #12 from Mic92/master

add travis ci
Update README.md

Added link to crowdin (translation crowdsourcing service)
Provisional fix for unit test.
Trying to fix .travix.yml
Added 4 icons.

icon_time, icon_repetition, icon_weight and icon_calendar
Added icon_history_black
Added icon_history_black
Implemented a first, working version of a dialog that displays the training history.
Added icon_calendar.
Removed button for showing a different training entry, added menu item instead.
Preparing release v0.3.1
Preparing release v0.3.1
Added many icons.
Addes shapes for buttons/lists/backgrounds.
Added background image, updated license texts.

Renamed imageView1 to imageview_logo.
Layout change for fragment_fex_detail.
Implemented adding/editing/removing FSets for the new layout.
Data model is now capable of saving whether a FSet has been done or not.
Data model: implemented clone() for FSet.

Also added a test for that.
Bugfix for FSet.clone() and its tests.