The existing logic assumes that requests may raise timeout exception
but timeout exception is never raised unless timeout is explicitly set
in each request method calls. This introduces the timeout option and
use it in request method calls so that timeout is actually set and
handled by the logics.
Also the keystoneauth session options loaded in the vault driver is not
actually used. This change also removes it.
Change-Id: I8c354937c2c39a63f50c150b3e858826b6a78fe0
2af34f28f8