Automate merging rules from development (master) to stable (3.0)
This could be as simple as a script that we run before making each stable release to determine which changes to master should be ported to stable. One idea is to use the Alexa Top 1M domains list  to mark ruleset changes as higher or lower priority. Right now we just do this manually.
Another possible metric for "stability" is the amount of time that a ruleset has been in master without any bug reports.