Draggable 0.7.0

- Added new "trigger" functionality for defining a child element that serves as the initiator of dragging.

- Worked around several bugs in the stock browser of several Android devices.

- Improved performance by shifting rendering from mousemove/touchmove event handlers to the main requestAnimationFrame loop that drives GSAP.

- Improved algorithm for sensing the velocity of the user's mouse/touch.

- Fixed an issue that caused an error when the Draggable JS file was loaded BEFORE the <body> tag was declared.