Checks if volume can be attached

This patches makes a boot fail fast if one of the volumes cannot
be attached at boot time. Currently the request is accepted but
spawning fails in addition to leaving the volume state as
available which is an inconsistent state

fixes: bug 1166770
(cherry picked from commit 8e4eec840d504d27a3a4c640dba67b3b47e81730)

Conflicts:

	nova/tests/compute/test_compute.py

Change-Id: I35b2034f8aa9574fcb8a34b58ead9f5e9ef27664
Merge "Checks if volume can be attached" into stable/grizzly