Added PathConstraint support to Javascript API

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