Allow origin 2.0

The master branch of [mongoid/origin](http://github.com/mongoid/origin) has [a bug fix](https://github.com/mongoid/origin/pull/91) merged in that I am hitting when I recently upgraded to the master branch of mongoid. However, the master branch of origin has been bumped to version 2.0, while mongoid's master currently requires origin ~> 1.0.

I'm not sure what Mongoid's versioning policies are, but would it be possible to update the gemspec to allow origin >=1.0, < 3.0?