shortened MSAM name. Tweak cloak time

Mobile SAM launcher name shortened. 
Stealth tank time increased 80 -> 90 until https://github.com/OpenRA/OpenRA/issues/2898 is addressed.
Shortened a few other names.
Fixed some descriptions.
apc gun given recoil
APC muzzle flash made single shot inst. of double
set A.I. max silos to build == 1, to save space

Due to conyard build radius, unnecessary buildings should not be built.
Silo is not really needed, so capping to 1. 
Merge pull request #3007 from psydev/patch-1

shortened MSAM name. Tweak cloak time. Fixed desc's.