Fixing issue with editing N1K network profiles

This resolves issues surrounding the update network profiles
for the Cisco N1K profiles when used with the N1K neutron
plugin.

Issue resolved include the edit form opening up properly
and also addressing which fields are editable and which not.

Also adding new unit tests.

Closes-bug: #1260435

Change-Id: I318057a9f5870d4a25ebf461d5fc67e4a03d54d8

Conflicts:
	openstack_dashboard/dashboards/router/nexus1000v/forms.py
	openstack_dashboard/dashboards/router/nexus1000v/templates/nexus1000v/_update_network_profile.html
	openstack_dashboard/dashboards/router/nexus1000v/tests.py