Change unique constraint in VirtualInterface.

UC on column address changed to (address, deleted).
Used soft_delete instead of delete.
Migrate scripts updated.
Fix bug 1156227.

blueprint db-enforce-unique-keys

Change-Id: I2f9f92cae3c9e49e0f594437d130c1654f76a343
Merge "Change unique constraint in VirtualInterface."
Merge remote-tracking branch 'm_src_repo/citrix-fixes' into build-temp