1. Sync sphinx dependency with global requirements. It caps python 2 since sphinx 2.0 no longer supports Python 2.7. 2. Remove unncessary "==" Change-Id: I943243704442ae78a0acf8985b1cebe993d97828
Use https instead of http to ensure the safety Change-Id: Ie172d0e11ed00215694bd9320867e8b0917c847a
Added to devstack as well. Change-Id: I98eed46a8dd9918ba36c97fe40619ec42136c723