also install cgmanager.h

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
fix comments in xml

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
frontend.c: add some comments explaining the boilerplate

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
README: fill in a rough draft of the design description

Perhaps the README isn't the best place, but we can always move it
later.

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