Merge pull request #2671 from Wikia/bac-1251-if-none-match-support

BAC-1251: handle If-None-Match and disable the support of If-Modified-Since
Merge pull request #2667 from Wikia/bac-1250-wgInvalidateCacheOnLocalSettingsChange

BAC-1250: wgInvalidateCacheOnLocalSettingsChange - set to false
Merge pull request #2666 from Wikia/bac-1245-remove-ip-from-beacon-tracker

BAC-1245: do not add IP to Tracker beacon URL
Conflicts:

	extensions/wikia/Track/Track.php
Merge pull request #2678 from Wikia/release-207-varnish-caching-backports

Varnish caching backports to release-207