Add angular-sortable-view directive (MIT license)

Source: https://github.com/kamilkp/angular-sortable-view

This has no dependencies at all, unlike ngRepeatReorder which depends on
hammer.js and angular-hammer. Since ngRepeatReorder was failing on some
browsers on Windows (for example, the latest (as of this writing) stable
version of Chrome), and it was failing in a way that suggested that
event handling (of drag events, specifically) was the cause, we're going
to try replacing it with a directive that has no dependencies on other
libraries at all.
Picklist WIP: remove ngRepeatReorder demo

We're switching to a different base library, so let's remove the demo of
the ngRepeatReorder module that we're not going to use any longer.
Picklist: swap out which internal directive we use

Replace ngRepeatReorder with angular-sortable-view instead, since it has
fewer external dependencies and should be more reliable.