Making category sort keys work for blog posts

As of now, categories are using hardcoded sorting, ordered by username and blog title. This change allows custom sort keys added using {{DEFAULTSORT:sortkey}} or [[Category:Categoryname|sortkey]].
Update CategoryViewer::addPage hook handler in Answers

The changes made to the CategoryViewer::addPage hook in VOLDEV-29 necessitate an update of its handler answerAddCategoryPage in Answers.php so that it can process the extra parameter (string $humanSortkey).
Sean's changes extracted from https://github.com/Wikia/app/pull/2431
Special:Connect - no more accounts without email
Added trim() for validated fields
VOLDEV-38: remove block link for users without block right
VE-717: Editor survey
Adding WAM controller
Added onWFChange hooked event
Added hook on WF variable remove
Getting hidden wiki ids works
Better place for Remove Hook; Add/Remove working properly
Added maintenance script to collect hidden wikis
check for EditorSurvey before calling methods
remove quotation
code review cleanup
simplified constructor for UserIdentityBox, moved part of the method to newly created FavoriteWikisModel, added temporary solution for not displaying private wikis
VE-717: fix i18n messages
removing EditorSurvey calls from ViewPageTarget
oops, switching EditorSurvey.seen to EditorSurvey.set( 'seen' )