Hyper v multiple switches

[galthaus]

This adds ability to specify additional network adapter configurations. The existing templates should work in a backwards compatible way.

switch_config {
  switch_name = "Default Switch"
}

switch_config {
  switch_name = "sw1"
  switch_type = "Internal"
}

adapter_config {
  switch_name = "Default Switch"
}

adapter_config {
  name = "nic1"
  swich_name = "sw1"
}

Closes #86
Closes #114

[hashicorp-cla]

All committers have signed the CLA.