Add check for non empty name of dvSwitch
Add check for non empty name of dvSwitch

Name of dvSwitch (or physnet to switchname mapping) mandatory should be
setted.

Change-Id: I29c18896f19b914d0423eac6e0450f63eedb4858
Closes-bug: #1481010

stackforge/fuel-plugin-vmware-dvs,stackforge/fuel-plugin-vmware-dvs,stackforge/fuel-plugin-vmware-dvs,stackforge/fuel-plugin-vmware-dvs