Provisional Rails 4 updates; specs pass

 - Mongoid 4 uses upstream bson lib enforcing serialization with $oid;
   we unwrap by monkey-patching like promiscous ( http://git.io/cDladA )
 - Rspec 3 deprecations quieted
Yep. The alternative is refactoring all the shoulds to expected_to's. The latter is better, the former is easier :-)

c.f. https://www.relishapp.com/rspec/rspec-expectations/docs/syntax-configuration#explicitly-enable-both-syntaxes