Proper membership check in can.proposal.create (fixes #908)

Fixup 4cfefbe2920f276357462da424a8d7baa038d0e7.
Don't show sentiment in sectionpage comment edit form (fixes #899)

This is coherent with the create form.
Improve fix-autojoin flash message if autojoin isn't needed
Merge pull request #910 from nidico/feature-899-fix-comment-sentiment

Don't show sentiment in sectionpage comment edit form (fixes #899)
fix-autojoin: filter instances in database
Move fix_autojoin core from admin controller to user model

Note that this slows down the fix-autojoin admin action; but the usage
of this function is extraordinary anyway, so I don't think this matters.
Autojoin newly activated users (fixes #907)
i18n: extract and update
commit after User.fix_autojoin
avoid some commits in fix_autojoin admin action
refactor autojoin in User.create
Merge pull request #911 from nidico/feature-907-fix-user-import-autojoin

Fix autojoin on newly imported users
pep8
Add CHANGES for 2.4.4