Remove support for Ruby 1.9.2
Travis: Fix rubinius declaration (rbx -> rbx-2)
Appraisal: add gemfile for ActiveRecord 4.1, fix gemfile for ActiveRecord edge
Use `42` instead of `42.0` in spec examples to avoid typecasting errors with Arel 6
Add support for Arel 6 (ActiveRecord Edge)
Rakefile: add database specific spec tasks
Update Changelog
README: Switch to http://shields.io/ flat badges