nova: support to get consumed time of a thread
nova: determine number of CPUs
nova: add native_capability comparator
initial cpu_monitor

* wrap CPU interface
* add cpu_monitor interface
* add test client using cpu_monitor interface
* support for FOC and NOVA
foc: add support to get cpu idle times of kernel
nova: add support to get cpu idle times of kernel
cpu_monitor: provide cpu idle times

works for foc and nova