This patch adds cgset tool

This patch adds cgset tool

This patch adds cgset tool, which sets parameters of controllers
for given cgroup based on input name-variable pairs
- the syntax is:

cgset -r <name=value> <relative path to cgroup>

-------------------------------------------------
EXAMPLES:
$ cgcreate -g cpuset:test1
$ cgset -r cpuset.cpus=1 test
$ cat ./test/cpuset.cpus
1

$ cgcreate -g cpuset:test1 -g cpuset:test2
$ cgset -r cpuset.cpus=0 test1 test2
$ cat /mnt/cgroups/cpuset/test1/cpuset.cpus
0
$ cat /mnt/cgroups/cpuset/test2/cpuset.cpus
0

Signed-off-by: Ivana Varekova <varekova@redhat.com>
Signed-off-by: Dhaval Giani <dhaval@linux.vnet.ibm.com>