Disable rendering logging in production

Update help

Single post view interaction refactorings

Use config.eager_load_paths instead of config.autoload_once_paths

See http://guides.rubyonrails.org/upgrading_ruby_on_rails.html#autoloading-is-disabled-after-booting-in-the-production-environment

Since the gem was renamed, we need to require it manually...

Upgrade to rails 5.1

Otherwise Rails 5 would ignore the migration version and create the
tables with bitints as IDs on MySQL.

we released that in 0.5.0.0 in 2015, we do not support skipping majors
anyway, and this is broken in Rails 5, so let's remove this. If people
upgrade from before 0.5.0.0, they have to upgrade via 0.6.0.0, but
that's written in the documenation.

Although this is contrary to rails best-practises, we cannot provide a schema.rb that works for both MySQL and PostgreSQL, so we have no choice. Our migrations are maintained, so it should always be possible to get back to a "clean" database schema anyway.