rspec stopped explicitly requiring expectations

It seems that rspec stopped requiring expectations and mocks explicitly https://github.com/rspec/rspec/commit/15ef280ac74b03f612d6038f484d80226fb38e03 Because of that I always getting following error. This should fix error.

`undefined method 'define' for RSpec::Matchers:Module`  `/mongoid-rspec-1.9.0/lib/matchers/document.rb:89`