add AppColors as a category on UIColor
add salmon as a class method in AppColors
import AppColors in PlaybackBar header
use salmon when setting PlaybackBar's background
import AppColors in AddRecordingViewController header
use salmon when setting layer colors in AddRecordingViewController
import AppColors in FeedViewController header
use salmon when setting cell bg color in FeedViewController
import AppColors in SettingsViewController header
use salmon when setting button color in SettingsViewController