Don't double ActiveRecord::Base in specs

The method stubs can be used on the real object instead.
Convert the Arel query object to a SQL string before executing it.
Fixed issue after unhash did not use the result.
Add basic integration test using real ActiveRecord
Merge pull request #4 from dnrce/test-activerecord

Add basic integration testing with ActiveRecord
Merge pull request #5 from dnrce/rails3.0-arel

Convert the Arel query object to a SQL string before executing it
Merge pull request #6 from dnrce/unhash-result

Fixed issue after unhash did not use the result.