Log Message:
Update databases/ruby-dm-types pacakge to 1.2.1.

* Support for Resource#dirty? upon indirect property mutation was added (this
  is huge, more info here:
  https://github.com/datamapper/dm-types/commit/3d96b1cd2b270a3843877a5...)
* Issues with Paranoid properties and STI were fixed
* JSON property uses multi_json now