Testing

I've added a test for the library and I'm using travis to track after pushing code to github.
In MAC all test are ok.
in Ubuntu all test are ok.
In travis platform fails in the disk methods, can you validate this?


Before push a new version of rubygem we have to ensure that all test are ok.

Also, I deleted one method called `diskio` because both was the same code.

Please run the test in your machine with `rake`command.