Add Rails logger check

[tyler-eon]

If Rails is defined, use the Rails logger.

[tyler-eon]

I ran the tests using ruby 2.1.2p95 and everything is green. I'm not sure why ruby-head is failing on Travis-CI; perhaps the way URI parsing is done has been changed, either by choice or by accident? Regardless, I would appreciate it if someone else could try this out and see if it actually works using a stable Ruby build. Thanks.