Model#update_attribute now uses the setter:

Previously had used write_attribute under the hood, and would not work
with users who had overridden the setter themselves.

[ fix #3075 ]
Include specs in gemspec.

[ close #3077 ]
Fix failing spec with dynamic attributes
Fix spec runs on non standard mongod ports.

[ fix #3068 ]
validate errors against the new instance after using Document#becomes
Update changelog