Ruby Rails with CQ5.6

You can use Maven to build components that a CQ apps uses such as OSGi bundle. See this community article as an example of how to use Maven to to build an OSGi bundle (in this example - the OSGi bundle contains JCR API logic that persists data to the CQ JCR) :

http://scottsdigitalcommunity.blogspot.ca/2013/01/persisting-cq-data-in-java-content.html

I have not worked with Ruby on Rails; however, you can you integrate Ruby on Rails and CQ by using Ruby on Rails to submit RESTFul sling requests to CQ. As an example - read this community article that uses a .NET application to submit a RESTFul sling requests to post data from a C# .NET app to the CQ JCR:

http://scottsdigitalcommunity.blogspot.ca/2013/06/submitting-data-to-adobe-cq-jcr-using.html

Here is another example of using an App to sent Restful sling requests to CQ:

http://scottsdigitalcommunity.blogspot.ca/2013/05/submitting-mobile-data-to-adobe-cq.html

Hope this helps