Don't load the glance when it's not needed
Don't load the glance when it's not needed

Fixes #13

If the user doesn't specify the --register-with-glance option, the
python-glance or python-glanceclient library should not be needed.

Signed-off-by: Tomas Sedovic <2bc6038c3dfca09b2da23c8b6da8ba884dc2dcc2@sedovic.cz>

sdake/heat-jeos,steveb/heat-cfntools,steveb/heat-cfntools,openstack/heat-cfntools,bbandaru/heat-cfntools