CKRM CPU resource controller

This patchset adds a CPU resource controller for CKRM.  The CPU
resource controller manages CPU resources by scaling timeslice
allocated for each task without changing the algorithm of the O(1)
scheduler.

Patch descriptions:
1/9: cpurc_load_estimation
	- Adds class load estimation

2/9: cpurc_hungry_detection
	- Adds class hungry detection

3/9: cpurc_timeslice_scaling
	- Adds CPU resource controll by scaling timeslice

4/9: cpurc_interface
	- Adds interface functions to CKRM CPU controller

5/9: cpurc_docs
	- Documents how the CPU resource controller works 

6/9: ckrm_cpu_init
	- Adds the basic functions and registering the CPU controller
	  to CKRM

7/9: ckrm_cpu_shares_n_stats
	- Adds routines to change share values and show statistics

8/9: ckrm_cpu_hotplug
	- Adds cpu hotplug notifier for the CPU controller

9/9: ckrm_cpu_docs
	- Documents how to use the CPU controller

Thanks,
MAEDA Naoaki