Enhancement: Make sortable via touch for mobile

[knownasilya]

Probably the most needed feature.. jquery-ui's sortable doesn't support it, but there are some hacks on the web. Maybe pick the best one, clean it up and add it.

[knownasilya]

Another option is to not use jquery-ui, but something like https://github.com/RubaXa/Sortable

Especially since jquery-ui is kinda bloated.

[justinph]

@knownasilya I've had luck using jQuery Touch Punch: http://touchpunch.furf.com/

[omghax]

I'll admit that jQuery UI is bloated, but it's also well-tested. I can use jquery.simulate to write my own unit tests against it, like so: https://github.com/IvyApp/ivy-sortable/blob/master/tests/unit/views/ivy-sortable-test.js#L80-L84.

I would love to move to something more lightweight that made use of native HTML5 drag and drop, but unfortunately the libraries I've looked at weren't built with testability in mind. If you've found any that are, I'd be willing to take a crack at integrating them.

[knownasilya]

@omghax will keep a look out.

[knownasilya]

@omghax what about https://github.com/bevacqua/dragula, although no tests once again..