add log for _get_images method
add log for _get_images method

The _get_images method in glance/registry/api/v1/images.py doesn't
give logs when catch exceptions. Two logs for two different
exceptions will be very useful for debug.

Change-Id: I5725da0dafdb9909de1c31734b3c1c225483ca66
Closes-Bug:#1263871

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