Fix the validation flow in the WSServer
create a notification manager
use the notification manager for the 'copy to clipboard' success notification
display an error notification when we can't access the camera. fixes #122
add style for error text notifications
remove deprecated code
do not check the error code when audio/video retrieving fails
Merge pull request #163 from Paulloz/wsserverflow

Fix the validation flow in the WSServer
Merge pull request #171 from Paulloz/nocameranotification