Deprecated #type

Mash tries to call `super` in the #type method, which causes issues in Ruby 1.9.2, as it no longer exists. It's deprecated from 1.8.7 anyway, so i replace `super` with `Hashie::Mash`.

Tests didn't pass on 1.9.2 before, but now they do both on 1.8.7 and 1.9.2.

thx