LP#1350457: Pass caller's session to subrequests called via method_lookup

In the process of looking up a method for an internal subrequest, we lose
session info. This is a problem when the subrequest makes a remote request,
because then the subrequest can't look up the proper locale, among other
things. The forthcoming branch passes the caller's session to the subrequest.

Signed-off-by: Mike Rylander <mrylander@gmail.com>
Signed-off-by: Galen Charlton <gmc@esilibrary.com>