Refactor openstack new_vminstance method

Change-Id: I33bba6d4ce911e6429835d93705f9b7f4704ebae
Signed-off-by: Gulsum Atici <gulsum.atici@canonical.com>
(cherry picked from commit 26f7366ed0ab69a4c7c3e0bc2fdd51f35b36c396)
3 files changed