remove the perm part from cgsnapshot output if possible

remove the perm part from cgsnapshot output if possible

This patch removes perm part from cgsnapshot output if it
is set to the default one:

EXAMPLE:
old version:
# Configuration file generated by cgsnapshot
mount {
	memory = /cgroup/cpu2;
	devices = /cgroup/cpu3;
}

group CBSFxx {
	perm {
		admin {
			uid = root;
			gid = root;
		}
		task {
			uid = root;
			gid = root;
		}
	}
	devices {
		devices.deny="a *:* rwm";
		devices.allow="a *:* rwm";
	}
}

new version:
# Configuration file generated by cgsnapshot
mount {
	memory = /cgroup/cpu2;
	devices = /cgroup/cpu3;
}

group CBSFxx {
	devices {
		devices.deny="a *:* rwm";
		devices.allow="a *:* rwm";
	}
}

Signed-off-by: Ivana Hutarova Varekova <varekova@redhat.com>
Acked-By: Jan Safranek <jsafrane@redhat.com>
Signed-off-by: Dhaval Giani <dhaval.giani@gmail.com>