Raise exception when poll returns error state

When running nova boot --poll, any error states that occur will be
seen but, an exit code of 0 will be returned indicating success.
This would be problematic for scripts looking to see if an
operation completed successfully.

To fix this, an exception is raised after the nova api indicates to the
poll code that the vm is in an error state. The exceptions signals the shell
main function to exit with code 1.

Change-Id: I48f6b1c82e2f8b221dda898dcb804b0196018505
Fixes-Bug: #1292669
Fix for invalid literal ValueError parsing ipv6 url(s)

Switch to using network_utils for splitting the URL. The code
in oslo-incubator supports ipv6 urls

HEAD of oslo-incubator is bb52a3fc49f033b9f36238231ca56e754a78cf4b

Updated openstack-common.conf to pick up the new dependency from
oslo-incubator

Change-Id: Ifa3dec384e85942a191260d17e8141030d31ff84
Closes-Bug: #1298137
Merge "Fix for invalid literal ValueError parsing ipv6 url(s)"
Merge "Raise exception when poll returns error state"