add migration support for lb security groups

This is a companion change for the security group models.

Change-Id: If8a75004ddb4e20fb8491529ac7098828edb5c7d
Pass X-Forwarded-For header to Nova

fixes bug 1097524

Add X-Forwarded-For header to the proxied Nova metadata request. Nova
needs this value to properly answer /latest/meta-data/local-ipv4
requests.

Change-Id: Icaec38b2ca7e06b50960deb7ab24ff1944a81f45
Merge "add migration support for lb security groups"
Merge "Pass X-Forwarded-For header to Nova"