conpaas: allow to detach storage volumes from running instances


git-svn-id: svn://svn.forge.objectweb.org/svnroot/contrail/trunk/conpaas@5231 ef35cc4a-2640-4bbf-98bc-65920db7d8ae
conpaas: remove unused imports from test_manager.py


git-svn-id: svn://svn.forge.objectweb.org/svnroot/contrail/trunk/conpaas@5232 ef35cc4a-2640-4bbf-98bc-65920db7d8ae