Added PathConstraint support to Javascript API
To create a new PathConstraint:
var pathConstraint = new dali.PathConstraint( myPath, [1.0,0.0] );
To apply the path constraint to an actor:
actor.applyPathConstraint( pathConstraint, "position", actor, "color-alpha" );
actor.applyPathConstraint( pathConstraint, "orientation", actor, "color-alpha", [1.0,0.0,0.0] );
The code above will constraint position and orientation of the actor to the path. The parameter to sample
the path will be the color-alpha of the actor.
Change-Id: I9d3f5c48f0e984d0626a0cf41b0ab2dcdd6d9516