sysvinit scripts: address some bugs

'service cgmanager start;  service cgmanager start;' caused cgproxy
to start.  Check whether cgmanager is already running to prevent that.

status was not checking the PIDFILE.  This could cause trouble when
running containers.

Split out restart from start, and make it actuall stop cgmanager.

If start fails, return an error code.

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
Merge branch 'master' of git://github.com/cgmanager/cgmanager