initial Rails 4.0 compatibility - ActiveRecord::ConnectionHandling
got introduced and is expected to contain the "#{config[:adapter]}_connection" instance method (instead of having it on ActiveRecord::Base's singleton class)
ActiveRecord::AbstractAdapter#exec_insert has 5 args in AR 4.0 (master)
enable running tests with activerecord 4.0 (rails master)
31 is the greatest DECIMAL precision allowed in Derby
cleanup H2 / HSQLDB adapter - HSQLDB should not know about H2