[TS] Add Nod Stealth Generator and GDI TechCenter to the AI 

The AI can now build:
- Nod Stealth Generator (Nod)
- Tech Center (Nod & GDI)
- Radar (Nod & GDI)
- Replaced GDI Transport (apc) with GDI Titan (mmch)

![untitled](https://cloud.githubusercontent.com/assets/2057932/4539383/5b747fb2-4dfc-11e4-8311-1bee2f0e8fa8.jpg)