(POOLER-167) Allow for network configuration at vm clone time

[rooneyshuman]

These changes check if a pool's configuration contains a network property. If so, at clone time, a vm's network device is reconfigured to the denoted network.

It is necessary to reconfigure the network device since all vm templates are set up to connect to network vmpooler.

The create_relocate_spec and create_clone_spec methods were also created to break up the work performed in the create_vm method.

[rooneyshuman]

This feature has been tested by:

1. Temporarily updating the configuration of one of the vmpooler-dev pools to the following:

  - name: "dev-pool-C-3"
    template: "templates/redhat-7.2-x86_64-0.0.3"
    folder: "vmpooler-dev/dev-pool-C-3"
    datastore: "tintri-pix-2-vmpooler"
    clone_target: "acceptance2"
    size: 3
    datacenter: "pix"
    provider: "vsphere-ci65"
    network: "ops

* Note the addition of the network property at the bottom. All vm templates are currently configured to be connected to the network named vmpooler.

2. Next, a request to vmpooler's /vm endpoint was sent in order to trigger the create_vm method.

3. The new vm's IP address and configured network were then checked through vCenter:
   

4. Finally, the vm was verified to be accessible via SSH: