libcgroup: Introduce the new namespace keyword

libcgroup: Introduce the new namespace keyword

This patch introduces a new keywork NAMESPACE which allow cgroups
to be created starting from a certain point as mentioned by the
administrator. This is provided via the configuration file.

Newer APIs will use this feature.

Changes from v1:
1. Attempted to fix the indentation
2. Change a variable name

Signed-off-by: Dhaval Giani <dhaval@linux.vnet.ibm.com>
Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com>