Raise descriptive error for over volume quota

If you attempt to create a new instance booting from an image and you
were over your quota on cinder, the nova manager would see that as an
invalid block device. This raises a more descriptive error message in
the logs.

Closes-bug: #1013417
Change-Id: Ie50b97c31580da7fc38c6891d1f3646b91f8aa10
Raise HTTPForbidden from os-floating-ips API rather than 404

The os-floating-ips extension was catching and handling a 404
and 403 in the same block and raising HTTPNotFound for both.

This change separates the 404 and 403 cases so HTTPForbidden
is returned in the 403 case.  For the 404 case, the test is
updated to raise the proper NovaException and a new test is
added for the 403 Forbidden case.

Change-Id: Id0daf2d61c6960d845d3b7980f96228fece41128
Merge "Raise descriptive error for over volume quota"
Merge "Raise HTTPForbidden from os-floating-ips API rather than 404"