Accept vCPE vfModuleNames in NB API

Accept vCPE vfModuleNames in NB API

This affects the vCPE custom flow.  You can specify zero or more
VF Module names (correlated with the model invariant UUID) in the
user parameters, like this:

  "userParams": [
    .
    .
    .
    {
      "name": "VfModuleNames",
      "value": [
        {
          "VfModuleModelInvariantUuId": "5366deab-be06-44c7-b4f7-77e657b78b25",
          "VfModuleName": "VGW:e2:25:25:25:%"
        }
      ]
    }
  ]

Change-Id: I673c04775bf5796079dc0ed19890e73e76820ac0
Issue-ID: SO-1213
Signed-off-by: Rob Daugherty <rd472p@att.com>