Bump version to 2.2.2

Merge pull request #123 from mkonikowski/master

Update documentation for .top

Fixes for active_record_uuid

Fix builds in Ruby 2.5

Explicitly add Rake to the development dependencies

Bump version to 2.2.1

Remove privacy from rating-related methods (closes #53)

Fix bundler cache

Only test against Rails 4 and 5

Merge pull request #121 from nicolasleger/patch-1

[CI] Remove useless exclusions

[CI] Remove Ruby EOL <= 2.2

[CI] Do not test incompatible Rails 3 for Ruby >= 2.4

[CI] Fix logs