Make it possible to delete the warnings

From Anonymous on 2015/01/15 22:40:41 +0000

I’m having trouble sleeping and I really don’t like seeing the red circle with the thumbs down, for example when my sleeping time is to low. It gives me the feeling that I’ve failed, not a nice way to wake up. Would be nice if you could turn that off.

Copied from original feature request: http://urbandroid.uservoice.com/forums/264867-sleep-as-android/suggestions/6969332-make-it-possible-to-delete-the-warnings