Basic implementation of LPM-related functions for MSP430 MCUs
Sets MCU frequency in 'board.h', instead of the common 'cpu.h' file
Added the LPM_UNKNOWN constant to the enum 'lpm_mode'
for respresenting unknown/unavailable LPM-related status.
function 'lpm_get()' now returns LPM_UNKNOWN by default
ccnl: remove energy mesurement code

This code causes some troubles with the heavy usage of hwtimer and
foating point operations.

Ref: https://github.com/RIOT-OS/RIOT/issues/495
Merge pull request #511 from mehlis/ccn-lite-follow-up-7

ccnl: remove energy mesurement code
document PROJDEPS usage in dist Makefile
Merge pull request #512 from LudwigOrtmann/dist_makefile_projdep

document PROJDEPS usage in dist Makefile
Merge pull request #459 from rousselk/msp430-lpm-freq

Msp430 lpm freq