Initial stab at UI for adding categories

* disable web open link when clicking the license in detail view
** add callout to a selector list with only one item ;)
* add 'categories' item in detail view
** calls out to a table view with cats
** and a table view + search box for looking up cats / recently used cats
Make license selector page localizable, include a web link

Web link goes to (localized version of) https://commons.m.wikimedia.org/wiki/Commons:Licensing
work in progress -- cats pag
Update data model to include 'categories' string

Contains pipe-separated values.
*Should* work with automatic lightweight migration. I hope.
Category shortlist
stub controller for cat search
Retool some stuff to put cats list in detail view

Conflicts:
	Commons-iOS.xcodeproj/project.pbxproj
Merge remote-tracking branch 'origin/master' into cats-work

Conflicts:
	Commons-iOS.xcodeproj/project.pbxproj
	Commons-iOS/CommonsApp.m
	Commons-iOS/messages/messages-en.json
	Commons-iOS/messages/messages-qqq.json
Adjust reveal button placement in license cell
Category search mostly works!

Not yet hooked up to save...
Category search cells now include disclosure accessory to load web page
todo
make cat selection mostly work \o/

* no storage for recent cats yet
* cats don't update when going back a level
* explosions!
* doesn't save anything yet
Fix explosions
Category details screen with remove & info links
Make saving categories actually work
Add data model for recent categories list
Save categories, show recent cats

Almost works, but saves dupe entries.
Fix lookup of categories (prevent dupes)
Localisation updates from http://translatewiki.net.