Changed hints style (and small quick fixes)
perf(challenges): use some query & elemMatch magic on memberCount to reduce challenges.list overhead. memberCount is now updated when leaving/joining challenges
fix(groups): use proper mongo queries to handle guild/party access in
groups.get, fixes #2664
refactor(groups): re-rig group.get query compound-index order, so we can
make use of only one compound index
perf(challenges): use proper elemMatch in challenge.getMember so we
don't have to sift through which tasks are challenge tasks
Merge pull request #2911 from thepeopleseason/github-2832

Updated subscriptions to include Mystery Item perk
fix(groups): default group.privacy='private'. Starting now,
group.privacy is a required field due to certain queries
fix(views): indentation issue, fixes #2913
chore(Merge): remote-tracking branch 'marcgenesis/develop' into develop

Conflicts:
	views/options/settings.jade
fix space issues: contrib modal, challenge list