restapi : if "filter: ..." header is set, use query instead of search to list items

When the filter option is specified the api query should not
throw a insufficient permissions exception. Instead the query should
return a list of objects that the user has permissions for.

This patch fixes /events/{id}

Change-Id: Ia2ab0e1e62b9cc67fad51da5e5e0b2c1163087a6
Bug-Url: https://bugzilla.redhat.com/869334
Signed-off-by: Ravi Nori <rnori@redhat.com>