memcache: Reduce compression threshold for rendercache.
terminate_campaign: pass location to edit_campaign.
Set default geotargeting country correctly.
CommentTreeStorageV1.add_comments: write parents first.

When assembling a comment tree it's necessary that all comments
are present in parents. Writing parents first ensures this.
POST_submit: add hook for when banned domain submitted.
media: Make hooks for adding scrapers into the mix.
SRMember: Start dual-writing to a dedicated cache pool.

This is one of the most heavily hit rels currently and the hope is that
pulling it out to its own pool will make the main cache more effective
for everything else.  It may make sense to move SRMember to a different
model such as a C* DenormalizedRelation in the future.
Missing RequirementException import
CommentBuilder: add timers.
terminate_campaign: immediately update promote status to finished.
VOrAdminSecret: don't check modhash on GET requests.
CommentBuilder: separate `comment` and `children` handling.
CommentBuilder: delete debug_dict.
CommentBuilder: cleanup logic for selecting candidate comments.
CommentBuilder: move sorting/updating candidates to its own method.
CommentBuilder: don't import TimeoutExpired.
CommentBuilder: don't log when there's an empty candidates list.
CommentBuilder: use better variable name wrapped_by_id.
CommentBuilder: calculate num_children on the fly.
CommentBuilder: use heapq to keep sorted list of candidate comments.