Removed ActiveSupport::SecureRandom in favour of SecureRandom from the standard library. (It has been deprecated in the 3-1-stable branch.)

Replace references to ActiveSupport::SecureRandom with just SecureRandom, and require 'securerandom' from the stdlib when active support is required.

Removed the AS core_ext/kernel/debugger breakpoint method as this method is added by ruby-debug and should be left as is. Missing tests added.

Check for Module.new.dup as well in https://github.com/rails/rails/blob/master/activesupport/lib/active_support/core_ext/object/duplicable.rb

Don't print deprecation warnings every time the user reads or writes an inheritable attribute.  The warnings on declaration is enough.

Remove a circular require in AS deprecations. This is safe as AS deprecations is autoloaded as needed.