Rails 4.2 compatibility

[pgolm]

This fixes #82

[pencil]

Thank you for your contribution. I think we should be at least a bit pessimistic, since we don't know if Rails 4.3 could break CASino. Something like '>= 4.1.0', '< 4.3.0' for example?

[pgolm]

Thanks for your review! 😄 Yes, we can do this, but on the other hand we can add this if we know about some compatibility issues.

In the blogpost about the Rails 4.2 release the devs wrote:
"[..] Rails 4.2 also marks the last big release in the 4.x series. With this release out, we're now working towards the big Rails 5.0! This means rails/master is now targeting 5.0. [..]".

So I think we shouldn't have problems with this. But it's your choice 😅

[pencil]

Closed by #84