When novaclient isn't using a session from keystoneclient, it needs to
set reasonable TCP Keep-Alive values otherwise the operating system
defaults may cause the client to hang for hours before a connection will
time out. Using keystoneclient's adpater (which sets good defaults) will
allow us to not have to maintain this adapter here and to benefit from
their defaults.
Closes-bug: 1477275
Related-bug: 1323862
Depends-On: Ibd53ae2d4d2455db0ebc9951e5c764befc57850f
Change-Id: I1924bd96eb1a4bac5d57a5cc5d5461acb3f7f5ac