Functionality changes to the following flags

--group-add
	--blkio-weight-device
	--device-read-bps
	--device-write-bps
	--device-read-iops
	--device-write-iops

--group-add now supports group names as well as the gid associated with them.
All the --device flags work now with moderate changes to the code to support both
bps and iops.
Added tests for all the flags.

Signed-off-by: umohnani8 <umohnani@redhat.com>

Closes: #590
Approved by: mheon

pkg/chrootuser/user.go

@@ -69,3 +69,8 @@ func GetUser(rootdir, userspec string) (uint32, uint32, error) {
 	}
 	return 0, 0, err
 }
+
+// GetAdditionalGroupsForUser returns a list of gids that userid is associated with
+func GetAdditionalGroupsForUser(rootdir string, userid uint64) ([]uint32, error) {
+	return lookupAdditionalGroupsForUIDInContainer(rootdir, userid)
+}