ArticlesApiController: PHP hinting
ImageServingController: use JSON format by default
ImageServing: cache images with maximum limit

ImageServing::getImages() will take a slice when getting data from cache
ImageServing: mark getThumbnails() as deprecated
Merge branch 'dev' into bac-734-image-serving-results-caching

Conflicts:
	extensions/wikia/ImageServing/drivers/ImageServingDriverBase.class.php
	extensions/wikia/ImageServing/drivers/ImageServingDriverUserNS.class.php
update jquery.makeCollapsible from mw v1.21.1
VOLDEV-32 make jquery.makeCollapsible compatible with sortable tables
remove whitespace
hide/show sortable subheadings
Add some colors to Special:AbTesting page; add general information about currently used GA Slots
Minor changes suggested after in-team Code Review
Minor refactor
Remove zero state of Forum related discussions module
Add scheduled informations
Forgot to sort future GA slots
Obsolete styling in controller
revert back to 1.19 version
reapplying VOLDEV-32 fix
Merge branch 'VideoSprint42' into VID-125
Video (VID-125): Screenplay - fixing space