Add ruby-version, require rubygems

Just a hunch, but try this: 

I've got it successfully running on osx after making sure I had the right symlinks in place - are you trying to run this on windows?

One more thing to note - in order to get all of the dependency extensions built, I had to run

```
sudo ln -s /usr/local/Cellar/libffi/3.0.13/lib/pkgconfig/libffi.pc /usr/lib/pkgconfig
sudo ln -s /usr/local/Cellar/libxml2/2.9.1/lib/pkgconfig/libxml-2.0.pc /usr/lib/pkgconfig
```

What are you using for ruby versioning? This is also highly recommended as opposed to using system rubies
This will force whatever you are using for versioning (and anyone else using your project) to recognize this as a `1.9.3` app and look in the right places for dependencies.