If a VOLUME_SIZE option is not defined in the base cloud configuration
then the default OpenStack boot selection should be 'image' not
'volumeFromImage' otherwise we are unable to properly take advantage of
all options provided by an OpenStack cloud.
Change-Id: I76ae042d598c9f7fa1868d4ea6a3566f8c6b8115 Signed-off-by: Andrew Grimberg <agrimberg@linuxfoundation.org>