Fixing bug #136 and #150: Giving admins option to disapprove a fingering...

... when it has been submitted. Changing disapproval to actually deleting the fingering as discussed with Susan (dialog is displayed to confirm that the admin would like to do this). Also updated any generalized dialog confirmation messages (such as ones that just said 'Are you sure?') to being more specific/detailed. Made all messages specify what action would take place if confirmed. Also added a notice that displays when a fingering is deleted. Changes also include adding a search filter for users to filter search results by keytype (alt, std, both).