Added OnCapture lua trigger and begun work on nod03a

Most of everything is working just fine :) The mission needs some testing by persons other than myself and i would like feedback on my lua script which im sure won't be perfect.

Changes from the original:
* Removed harv that was sitting in GDI base not needed since one is supplied by Refinery in OpenRA
* Moved humvee above player base further north so that it is not instantly seen by the player
* Scripted some basic attack waves based on my experience playing the mission in c&c 1.06r3 earlier today
* Reduced the amount of starting units available to the player for difficulty reasons
* This mission has one cell trigger point which was not scripted due to lack of support