CSV export on stream results filter on that stream

fixes #452
actually fix CSV export on stream results filter on that stream

fixes #452
display better error messsage for query errors

fixes Graylog2/graylog2-web-interface#392
allow showing the users list for everone

the actual content will be limited to whatever the user is allow to see, at the least their own account, to be able to reach the edit page (to change their password, for example)
Merge git://github.com/Graylog2/graylog2-web-interface into develop