CLC-3689 Not-yet-working approach to LiveUpdatesEnabled mixin
CLC-3689 Make the LiveUpdatesEnabled tracker work in both the web thread and the message thread
CLC-3689 Remove MERGED_FEEDS and associated code
CLC-3689 Make user-cache-expiration a mixin
CLC-3689 Call UserCacheExpiry and UserCacheWarmer directly, instead of via constants, and get rid of the last bits of cache_tools.rb
CLC-3689 Make sure classes are actually expiration or live updates compatible
Merge pull request #2492 from ctweney/clc-3689

CLC-3689 Making LiveUpdates and User-cache-expiration a mixin