pkg: contiki/cooja integration

This will add Contiki OS and the network simulator Cooja [[1]](http://soda.swedish-ict.se/2296/1/SICS-T--2006-05--SE.pdf) to pkg.
Cooja in conjunction with mspsim is able to simulate whole networks consisting of
MSP-430 compatible platforms (various ATmega128* platforms are also supported through avrora[[2]](http://compilers.cs.ucla.edu/avrora/)). 
The simulator does not only support cycle accurate simulation of nodes but also a range of 
different models for wireless networks (ranging from simple unit disk graphs to ray
tracing based interference models).

TODO:
- [X] add contiki and cooja to pkg.
- [ ] integrate cooja into pytermcontroller (and testbed abstraction)
- [ ] ...