fix typos
Merge pull request #10953 from acapilleri/fix_typos

fix typos
'json' gem is no more required under JRuby
cleanup, remove trailing whitespace from AR changelog
regression test + mysql2 adapter raises correct error if conn is closed.
Merge pull request #10925 from senny/10917_test_to_prevent_regression

regression test + mysql2 adapter raises correct error if conn is closed.
Merge pull request #10955 from arunagw/jruby_json_not_required

'json' gem is no more required under JRuby
fixture setup does not rely on `AR::Base.configurations`.

As you can also configure your database connection using `ENV["DATABASE_URL"]`,
the fixture setup can't reply on the `.configurations` Hash.

As the fixtures are only loaded when ActiveRecord is actually used
(`rails/test_help.rb`) it should be safe to drop the check for an existing configuration.
Merge pull request #10907 from senny/fixtures_and_database_url

fixture setup does not rely on `AR::Base.configurations`.