Searchable issues solved #367

Solves issue #367, also includes pull request #401 for throttled notifications

If #401 for throttled notifications is not wanted I can redo with only the relevant code for searching 

Apologies if having the two pull requests open is inconvenient.

Also I have taken out the use of "problems/all" page (although I haven't deleted it in case you wanted to keep it - just commented out) in order to make "problems/index" consistent with "app/:id/show" so that the search can be used in both.

Cheers