Refactor _load_support_matrix
Refactor _load_support_matrix

In the Sphinx extension, split up the _load_support_matrix method, so
its easier to understand the additions for the feature_classification
table.

Change-Id: Ic3654017f63dda2c2505057b0063acbc6d5f83c2

klmitch/nova,phenoxim/nova,dims/nova,BeyondTheClouds/nova,alaski/nova,openstack/nova,dims/nova,zhimin711/nova,Juniper/nova,rajalokan/nova,zhimin711/nova,Juniper/nova,hanlind/nova,cernops/nova,gooddata/openstack-nova,sebrandon1/nova,cernops/nova,cloudbase/nova,vmturbo/nova,sebrandon1/nova,rahulunair/nova,vmturbo/nova,cyx1231st/nova,vmturbo/nova,hanlind/nova,Juniper/nova,bigswitch/nova,rahulunair/nova,vmturbo/nova,klmitch/nova,cernops/nova,jianghuaw/nova,mahak/nova,mikalstill/nova,cloudbase/nova,sebrandon1/nova,NeCTAR-RC/nova,Juniper/nova,CEG-FYP-OpenStack/scheduler,jianghuaw/nova,hanlind/nova,mikalstill/nova,gooddata/openstack-nova,CEG-FYP-OpenStack/scheduler,phenoxim/nova,openstack/nova,cloudbase/nova,bigswitch/nova,mahak/nova,mikalstill/nova,BeyondTheClouds/nova,BeyondTheClouds/nova,alaski/nova,jianghuaw/nova,gooddata/openstack-nova,mahak/nova,rajalokan/nova,klmitch/nova,gooddata/openstack-nova,klmitch/nova,jianghuaw/nova,openstack/nova,rajalokan/nova,rajalokan/nova,rahulunair/nova,cyx1231st/nova,NeCTAR-RC/nova