v1.2.1
Add missing changelog entry for 1.2.1

Whoops, forgot to save (and thus commit) the file with the release).
Update sqlite3 for Ruby 2.2 while maintaining Rubinius fix
Test on Ruby 2.2
Use Travis's new container-based infrastructure.
ActiveRecord 5 is Ruby 2.2 only, so don't test it w/ Ruby 2.1