Support VNF create with direct VNFD template input

Currently VNF Catalog is an integral part of Tacker solution. VNFD template should've been populated in the VNF Catalog before can instantiated. However, when Tacker is used just as a G-VNFM there are scenarios where the VNF / NFV Catalog exists outside Tacker. For those solutions it doesn't make sense to use Tacker's VNF Catalog. This blueprint will bring in the support for making VNFD id optional for tacker vnf-create. Instead support an option where VNFD template can be passed in directly to the vnf-create API / CLI.