Android longClick x, y, and duration support

Ruby examples:

mobile :longClick, element: el.ref

mobile :longClick, element: el.ref, duration: 3000

mobile :longClick, x: 400, y: 297, duration: 3000

mobile :longClick, x: 0.5, y: 0.244
Merge pull request #1945 from bootstraponline/master

Android longClick x, y, and duration support