Add a possibility to mount sources as volumes to containers,
in "more than documentation" way. That will let us to use kolla
as a replacement for devstack.
Co-Authored-By: ZhijunWei <wzj334965317@outlook.com>
Partially implements: blueprint mount-sources
Change-Id: I7db7d7f0d13a4a17d1884f2cb6fa6f2c37cb0e2b
bf71e336d4