Make scheduler rpcapi use object serializer

The scheduler rpcapi is still using NoOpSerializer which can't serialize
objects. When testing with objects for instance flavor, filter_properties
can not be serialized because its structure is:

{'instance_type': <nova.objects.flavor.Flavor object at 0x6862d10>,
'scheduler_hints': {}}

If the scheduler uses objects, its serializer can not be NoOPSerializer.

Related to blueprint icehouse-objects.

Change-Id: I0a9a02eefc051738183e0393ae0c462d60c74fef
Remove uneeded dhcp_opts initialization

Change-Id: I4fcb977f01b2d22fb445d11ad6953fc1bfaff4a8
Merge "Make scheduler rpcapi use object serializer"