6_2_X_SLHC12 Fixes for GEM geometry

Temporary bugfix  GEM geometry RPZ projection:
![screen shot 2014-05-20 at 15 47 27](https://cloud.githubusercontent.com/assets/2516492/3070223/93ef4096-e2a6-11e3-9a7b-96796e52b3fc.png)


Note, values of station, rings, etc. are hard-coded. To draw all GEM nodes (~430) it would be too much. Therefore wee need to get bounding box of each station. 

@ianna is there a way to get mother volumes in reco geometry?