Add room deleted page that is displayed if room member is viewing the
room when it is deleted by the creator
Add trash icon to the right of the edit room title icon. eraseRoom
method is called when clicked
Modify eraseRoom method to check user is admin OR creator before
deleting. Also sends new room deleted message that informs room members
that the room has been deleted. We can't observe room deleted because
it's also called when the room name is changed.