Implement ListKeys, ListControllers, and Prune

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

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
make ControllerList show comounted controllers

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
listkeys: take a cgroup as argument

freezer:/ has a different list of files than freezer:/foo.

So go ahead and take a cgroup name and return the actual list
of files under that.  Long as we're doing this, also add an
SCM version and ensure cgroup names are sane.

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
xml: add description of Prune

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
cgm: add new calls

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

there is still question about the right api for listkeys - should we
return ownership+perms (at a huge perf hit), and if not then should
we just return the same files for all cgroups (which we could then
pre-calculate at startup).

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
add prune and listcontrollers testcases

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
build_controller_mntlist: handle circular linked list

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
quiet the prune testcase

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
cgmanager: pass right remove-on-empty flag to prune

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
account for premounting sadness in test24

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
test09: handle potential slowness in create

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
make sure notify_on_release isn't set in our memory cgroup before test

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
release 0.31

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