Deprecations and dependencies logger and controller failsafe_logger errors

The lack of parentheses in the calls to defined? in this commit is causing problems when logging deprecations, for example, the ActiveModel errors class tries to warn about deprecation and causes this error:

private method warn' called for [expression](String)

The backtrace points to:

/vendor/rails/activesupport/lib/active_support/deprecation.rb:17

Adding parentheses to this line fixes the problem:

logger = defined?(Rails) ? Rails.logger : Logger.new($stderr)

Similar changes are also needed in the other files touched by this commit - the fact that this wasn't picked up in the tests also suggests a hole in coverage :)

Sorry I haven't got time to put together a patch, but this should be a fairly quickfix anyway.