pkg: cooja network simulator integration

Alternative to #1921 with the difference that this PR contains only files required by cooja.
For that purpose I created a fork of cooja [[1]](https://github.com/phiros/cooja). There are two reasons for forking cooja:

* downloading the whole contiki repo in order to work with cooja seems like overkill
* sparse checkouts still contain a lot of versioning information which aren't needed 
(a sparse checkout of cooja results in a repo size of about 70M; my fork results in about 40M)
* maybe we want to customize cooja in the future in order to better fit our needs. Right now cooja is pretty contiki-centric.


The rest of the PR description is nearly identical to #1921 (for now):

This will add the network simulator Cooja [[2]](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[[3]](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 cooja to pkg.
- [ ] demonstrate scripting capabilities and nogui mode with a transceiver driver test 
- [ ] integrate cooja into pytermcontroller (and testbed abstraction)
- [ ] ...