Merge pull request #5 from Ansa89/master

Sync with main project
Merge pull request #6 from Astonex/master

Sync with main project
Update Polish translation
Merge branch 'zetok-translation'
Unblock users
Friends list wont appear empty when blocking friends
Stop crash when clicking on blocked user and stop user from trying to send messages to them
Add Tox DNS Discovery Verison 2
Updating version
Merge pull request #7 from Astonex/master

Sync with main project
Merge pull request #8 from Ansa89/master

Sync with main project
Italian translation: update

Sync'ed with 75b24a3b87cbdfeef07916923f67c5f082f9d426 and some fixes
Merge branch 'Ansa89-italian-translation'
Update Polish translation
Merge pull request #9 from Astonex/master

Sync with main project
Update README.md

Add two devices to "Known to work" list:
- Xiaomi Mi2
- Xiaomi Mi2s
Solve additional opening of the MainActivity from WelcomeActivity and deal with the back button pressed situation.
Merge remote-tracking branch 'upstream/master' into work
Add Ukrainian language
Merge branch 'ukrainian-language'