A/B / Split testing in rails 3.2

I am working on Lead generation website and I am redirected from diffrent website and coming to my application with different forms with different layout and fields. Application is in ruby on rails and it is on heroku.

This form loading is based on the traffic rule which is define on admin site like 70% form form A and 30% for form B.

I want to A/B test the both the form like which form is submitted more or user went to how many steps.I also want the analysis of all that test.

Please suggest me the gem or plugin i can use. If there is a better way to do via programming?