Adding support for swiping.
Added an actionLayer child to the GameLayer.  The actionLayer contains layers/sprites that get wiped out between new levels.  This fixes the flickering between layers on android bug.
Vehicle scaling is fixed on several tested resolutions.  This created a sprite intersection bug.
Fixed collision detection issues.
Changed spawn intervals and speed.  Added to TODO.  Cleaned up GameLayer a bit.
Speed and spawn intervals are now configurable per level instead of per lane.
Fix randomizer function.
Scale vehicles horizontally.
Fix randomValueBetween call.
Merging FixScaling into master.