Remove collection scoped search code.

This removes the code that added collection scoped search options to the
simple search block.

This functionality has been moved to the reposervice module as the
simple collection search block.
Merge pull request #2 from lyrasis/remove-collection-simple-search-overrides

Remove collection scoped search code.

Pull request https://github.com/lyrasis/reposervice/pull/6 also required.