Feature request: Allow user to customize order of subscribed calendars in left nav

[posita]

Apologies if this is redundant to #133 and/or #394, but my webdav calendar subscriptions are not sorted. They do not appear in alphabetical order or ordered by subscribe time. I'm not sure what designates the order, but it's not clear whether I can change that. (Drag-and-drop doesn't work.) What I would like to be able to do is have some intuitive way to customize the order of my subscriptions as they appear in the left nav.

ownCloud version: 10.11.0

Calendar version: 2.0.0