Introduce osops_search function.

There was much dupliced code in ip_location.rb. Much of this has been
moved into osops_search and called from the other search functions. The
interface for other cookbooks has stayed consistent. Osops_search may be
used directly in future, to allow more control such as searching by
role, recipe or both.
Merge pull request #123 from hughsaunders/refactor_search

Merged automatically by jenkins after successful build test