Added support for reconfiguring network adapter

Added support for reconfiguring network adapters. I've tested, locally, the following scenarios:

Move from distributed switch to standard switch
Move from distributed to distributed
Move from standard to standard
Move from standard to distributed

I am a little unsure about several of the checks so if there is anyone else working on the module that could take a look that would be great, but on our VMware esxi 5.5 all of those scenarios work, and with multiple network cards.

I didn't update documentation as it already mentions "vm_nic" in the "state: reconfigured" section, which implies that the functionality already exists (currently only exists for memory and CPU).