Remove autodoc and useless index docs
Remove autodoc and useless index docs

* Remove autodoc sphinx extension
* Ignore auto-generated 'api' docs
* Prevent the corresponding 'api' index from being created
* Prevent an empty 'index' page from getting generated

Related to bp glance-folsom-docs-cleanup

Change-Id: I82c9389f884ea4af853f1215731c051d1fb596e8

vuntz/glance,sigmavirus24/glance,vuntz/glance,jumpstarter-io/glance,redhat-openstack/glance,openstack/glance,ozamiatin/glance,klmitch/glance,darren-wang/gl,ntt-sic/glance,klmitch/glance,rickerc/glance_audit,darren-wang/gl,scripnichenko/glance,jumpstarter-io/glance,akash1808/glance,sigmavirus24/glance,JioCloud/glance,rajalokan/glance,cloudbau/glance,dims/glance,SUSE-Cloud/glance,stevelle/glance,dims/glance,rickerc/glance_audit,saeki-masaki/glance,tanglei528/glance,paramite/glance,citrix-openstack-build/glance,akash1808/glance,citrix-openstack-build/glance,JioCloud/glance,takeshineshiro/glance,tanglei528/glance,ntt-sic/glance,paramite/glance,wkoathp/glance,wkoathp/glance,scripnichenko/glance,saeki-masaki/glance,stevelle/glance,rajalokan/glance,ozamiatin/glance,cloudbau/glance,takeshineshiro/glance,SUSE-Cloud/glance,openstack/glance,openstack/glance,kfwang/Glance-OVA-OVF,kfwang/Glance-OVA-OVF,redhat-openstack/glance