Unit tests for some WMF extensions

Add unittests to several extensions present in the mw/core wmf branch:

AccountAudit
AntiBot
ApiSandbox
Calendar
CategoryTree
CentralAuth
CharInsert
CheckUser
CleanChanges
ClientSide
CodeEditor
CommunityVoice
ContactPage
CreditsSource
CustomData
DisableAccount
Disambiguator
DismissableSiteNotice
DoubleWiki
DynamicSidebar
ExtensionDistributor
FeaturedFeeds
GeoCrumbs
GlobalBlocking
GlobalCssJs
GlobalUsage
GoogleNewsSitemap
ImageMap

Will need to add more later on.

Change-Id: Ie1e3dbfedadae05bb319e1268a40f83119878aa9