Check settings.ini (or if specified, another ini file) and warn if it's readable/writable/executable by other users

Fixes #74
It's perfectly valid to have no config (e.g. testing)
Changes Statistic model to make it more useful

We don't store update a user's last_login, so we there's no point in keeping that data around

We now have two JSON fields that can store statical data on inboxes and emails (mean average per user, average number of headers etc)
update queue for model changes
Website: possibly the last class based views to be done plus more testing!
Case insensitive username forms
Merge branch 'master' into deploy

Conflicts:
	website