Tests added for glance/cmd/cache_pruner.py
Tests added for glance/cmd/cache_pruner.py

Related to blueprint glance-cmd+unittests

Integration test test_cache_pruner_main added to cover
chain of calls between glance/cmd/cache_pruner.py and glance/image_cache
module.
Unit test test_cache_pruner_main_runtime_exception_handling added to
cover exception handling for main() method of cache_pruner.py

Change-Id: I7d7b182260a407aed1288a5d136e03cbe029523f

wkoathp/glance,vuntz/glance,ozamiatin/glance,jumpstarter-io/glance,akash1808/glance,darren-wang/gl,klmitch/glance,klmitch/glance,JioCloud/glance,stevelle/glance,saeki-masaki/glance,JioCloud/glance,paramite/glance,tanglei528/glance,kfwang/Glance-OVA-OVF,tanglei528/glance,rajalokan/glance,takeshineshiro/glance,jumpstarter-io/glance,dims/glance,stevelle/glance,takeshineshiro/glance,redhat-openstack/glance,dims/glance,akash1808/glance,vuntz/glance,kfwang/Glance-OVA-OVF,redhat-openstack/glance,scripnichenko/glance,sigmavirus24/glance,scripnichenko/glance,openstack/glance,openstack/glance,saeki-masaki/glance,sigmavirus24/glance,darren-wang/gl,wkoathp/glance,paramite/glance,ozamiatin/glance,openstack/glance,rajalokan/glance