Update dependencies and Readme

Now that I think we are on the same page I'd like to start contributing again if that is ok with you. I didn't mean to cause drama or anything like that, I wasn't in a good place when I wrote that + I was burned out from school.

Onto the technical details of this PR

* Update rails to 4.0.10
* Bump Ruby version to 2.1.2
* Remove the debugger dependency and replace it with [byebug](https://github.com/deivid-rodriguez/byebug), the debugger fork for MRI 2.x.x
* Pointed the readme badges to the upstream repo (yours) rather than my fork (failing on my part)

Cheers
Josh