Refactor for gemspec and fixing an important bug

@zakird @butzopower 
I've seen some problems with the actual structure of the gem, for example: you can't add the raw github repository to a Gemfile to use the developer branch without awaiting for the gem release.

This is a quick refactor for the gem structure, and fix some problems with the binaries' names.

You could use this command too, to generate the gem.

```
rake package
```
Please let me know if there are some issues. I hope this could be useful.