Integration of Power Policy with NRM.

A power policy (See #11 (closed)) is integrated with the NRM so that the control of power happens at the NRM level and not the application. The policy needs contextual information from the application (time spent doing computation and in the barrier during a phase) for decision. This information from the application is provided to NRM using the downstream API (2feab004) by an application-specific (e.g. PMPI) library written in C/C++. Using this the NRM invokes the correct power policy.

Closes #10 (closed)