Update vswitch module to support keep-ip option

Packstack doesn't use this option yet, so this commit shouldn't
specifically affect it, but as foreman needs this option we need
to add it.

Change-Id: I741cec30611560d48fb2796925e76cb66102e0ba
Allow packstack to detect linux sub-interfaces properly

Change-Id: Iebc764c1bf9fa6639cb81f0aa9d45eab4c176424
Merge "Allow packstack to detect linux sub-interfaces properly"