CLOUDSTACK-4508 (WIP): Conditionally make VSM fields required

If VSM is active, and either traffic overrides are checked, make VSM
fields required.

** This creates new VSM fields, with '_req' appended to end of ID. API
calls need to be changes to account for this.
CLOUDSTACK-4508: UI > Infrastructure > clusters > add cluster dialog > make NexusVSM fields required only when Override Traffic is checked AND vSwitch Type is "Cisco Nexus 1000v Distributed Virtual Switch".
CLOUDSTACK-4508: UI > Infrastructure > clusters > add cluster dialog > VSM fields > pass only value of visible VSM fields to API call.
CLOUDSTACK-4508: UI > Infrastructure > clusters > add cluster dialog > hide both required NexusVSM fields and optional NexusVSM fields when hypervisor is not VMware.
CloudStack CLOUDSTACK-4484
Vmware - Not able to fetch userdata from guest Vms using http://<router-address>/latest/user-data