Oj dependency causes JSON parsing surprises

[fastjames]

We recently added this gem to a rails app that we are building, and we were surprised to see some behavior changes in other parts of our app. Because of the oj dependency here, we observed a change in how our app handled encoding and dumping of Infinity values. We were able to work around it by calling MultiJson.use but it makes me wonder if MultiJson might be a better fit for this gem. I couldn't find anything in the repo that indicated the specific reason for oj being here, so if we used MultiJson instead the library user could choose that or some other JSON parser. What do you think about this?