add have_a_version_with matcher

[emre-basala]

so we can use this in rspec
with

 widget.should have_a_version_with :name => 'Leonard', :an_integer => 1

[emre-basala]

Build failing, I will fix this and open the PR again

[batter]

Thanks for the PR. Good idea for a matcher, I just pushed up 6c7efd0, where I updated the matcher to have simplified syntax, and use our existing where_object method on the PaperTrail::Version class, which actually queries the database and should provide a performance boost over the pure Ruby sort 😄

[emre-basala]

great thanks! I didn't know about the where_object method, the matcher looks a lot cleaner with it