Make gem compatible with old polyamorous require

By providing `polyamorous.rb` in the `lib` folder, projects that
previously depended directly on `polyamorous` can just switch the
dependency to `ransack` without changing their calls to `require`.

Version 2.3.2

Version 2.3.1

2.3.0 release

Version 1.8.10

Version 2.1.1

Merge pull request activerecord-hackery#973 from powerhome/sort-by-sc…

…opes

Add support for sorting by scopes

Version 2.0.1

Version 2.0.0

Version 1.8.9