ccnl: fixed commenting style
ccnl: eliminated empty translation unit warning
make: rename VERSION into RIOT_VERSION

Building MSP boards gives an error, because `VERSION` is somewhere
defined in their toolchain as an integer.

This PR renames `VERSION` into `RIOT_VERSION`, because that's what it
is.
Merge pull request #1400 from Kijewski/riot-version

make: rename VERSION into RIOT_VERSION
Merge pull request #1362 from OlegHahm/ccnl_eliminate_warning

CCN_lite eliminate warning
Update CONTRIBUTING.md

Add comment about labels, hint at Development Procedures.
core/sched: clean up

- remove stray spaces
- remove TODOs:
    - MODULE_HWTIMER is not a module anymore
    - checking for NULL is necessary, at least without API changes:
      `sched_task_exit` sets `sched_active_thread` to `NULL`, then exits,
      afterwards `cpu_switch_context_exit` calls `sched_run`
core/sched: fix pid/tcb & refactor SCHEDSTATISTICS

pid and tcb_t were compared instead of pid and pid

SCHEDSTATISTICS:
- reduce hwtimer_now calls
- dont use thread_last_pid anymore
- increase readability
core/sched: remove MODULE_NSS helpers (API CHANGE)

remove thread_getlastpid and last_pid from the API, it is unused
cpu/lpc2387: fix unused parameter warning

mark 'mode' as unused in pwm_init
Merge pull request #1405 from LudwigOrtmann/pwm_fixup

cpu/lpc2387: fix unused parameter warning
native: remove stale TODOs and blank line

The values are quite OK.
Merge pull request #1376 from LudwigOrtmann/sched_fixup

core/sched fixup and optimize
native: enable reboot with tap

partially fixes #787
Merge pull request #1408 from LudwigOrtmann/native-cleaning

native: remove stale TODOs and blank line
Merge pull request #1410 from LudwigOrtmann/issue-787

native: enable reboot with tap
vtimer: fix vtimer_remove()
vtimer: minor style fixes
vtimer: unify and enhance interface

Currently the vtimer only accepts relative timestamps, even though it
uses absolute timestamps internally. This PR adds the parameter
`vtimer_absolute_t absolute` to every function, which is either
`VTIMER_RELATIVE` or `VTIMER_ABSOLUTE`.

`vtimer_sleep()` sleep uses `thread_sleep()` now instead of
`mutex_lock()` to allow spurious wake ups. A parameter `int *spurious`
is added, which is set to 0 if the wake up was not spurious.