add entries to Changelog about api changes

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
update clients to reflect new socket location

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
update tests to reflect new socket location

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>