Bugfixes for old_build_version and skipping ELBs

- Better check for old_build_version it can be nil or a empty string
  depending on how the user interacts on the CLI
- Skip blank ELBs, this time with feeling

Change-Id: I70a56b3d619125ce2256c06d49cc634ee7222b60
Merge "Bugfixes for old_build_version and skipping ELBs" into red_black