UI fixes in SettingsViewController:
- hide keyboard if return key pressed
- show clear button while editing
- change tintColor
UI fixes in QRReaderViewController:
- cange navigationBarStyle
- change tintColor
change default color of status bar
Refactored part with notification (see Effective Objective-C item 4, item 31 )
Merge pull request #13 from wiruzx/ui-fixes

Ui fixes
Merge pull request #14 from VladiMihaylenko/VladMihaylenko

Refactored part with notification
Updated Tox Core.
Moved NSNotificationCenter removeFromObservers to viewDidDisappear, removed now-useless Edit button in Settings.