Fix for issue #92 - The element's original transform is discarded

[Sphinxxxx]

Basically an updated version of pull request #93, but with a fix for rotated elements (see peterbe's comment in issue #92 here: https://github.com/desandro/draggabilly/issues/92#issuecomment-157452101), and elements with more than one transform property.

Implemented here: http://codepen.io/Sphinxxxx/pen/QyRRom

[desandro]

Thanks so much for this contribution! This is nice work.

While this issue has gotten some attention, I don't feel there's been enough to warrant adding a fix just yet. I'll keep this PR open so others can chime in.

[elcontraption]

This would be a great addition.

[ldetomi]

Ohhh I just opened #156 this morning to address this issue. Please, merge it!!! :-)