Make use of entry_poins for creating the binary for the module (#10)

This is for issue #10.
As explained in the link I added with the issue, I had to:
* move the script file inside the module,
* rename it to hold a .py extension,
* create a main method to be called from executable in entry_points
* to modify the script.py to hold entry_poins entity instead of scripts 

@warner can you have look at this and also release it to pypi?