Remove #:nodoc: for ActiveRecord methods needed outside of Rails

When using ActiveRecord in a framework other than Rails, you will need to use these methods:

• verify_active_connections! before handling each request, to ensure DB connection has not been dropped

• reset_subclasses before reloading model classes, otherwise you get strangeness like the same validations being performed multiple times.

However, both of these methods are marked #:nodoc:

The attached patch removes #:nodoc: and adds a brief comment as to the purpose of each one.