Adding support for query filtering to list() calls

Each of the list() methods now supports an extra
parameter, search_opts, which is a dict that will
contain search fields and values to limit the result
sets.  The changes here will also rely upon changes
to the Sahara service to support query-style
parameters.

Change-Id: I26986cbc153c3f8ad74b52d91086afbdfbd93926
Implements: bp enable-result-filtering
Merge "Adding support for query filtering to list() calls"