Currently the search API accepts resource_type as an optional param
which is used to limit the scope of the search to a given type of
resource. This in turn searches the backend for all fields of all
objects.
For example, a search for LogicalSwitch resource_type may return
NSGroups which contain a membership criteria for LogicalSwitch.
In this case NSGroups are returned since the target_type field for
the NSGroup is set to LogicalSwitch.
In order to correctly return only objects of type LogicalSwitch, the
query must have resource_type:LogicalSwitch instead of LogicalSwitch.
Change-Id: I0418c0a758b28ec46b77a7adaf2dbc3addac6da3