fix: ActiveRecord::Relation behaves like a array

We may not just put it into an array; instead treat it as an array
fix: avoid threads.length queries for hidden threads
more tests for CfMessage
fix: `find!` does not exist
new tests for CfCloseVote
a lot of testing for tags controller
bugfixes, found due to tests
fix: tag names are always small
fix: use right name for retag right
a lot of testing for messages controller
small refactoring for better readability
lots of tests for cf_messages_controller
removed legacy code
fix: use spaces instead of tabs
bundle update