unity mouse move zoom in zoom out
http://answers.unity3d.com/questions/301951/how-can-i-make-a-gameobject-scaleresize-with-mouse.html
iOS, Android, Unity3D Education blog,
http://answers.unity3d.com/questions/301951/how-can-i-make-a-gameobject-scaleresize-with-mouse.html
reference: Input.GetAxis Input.GetButtonUp sample code: b39_input_Input_GetButton
c# version javascript version. sample code: b36_iphone_input