Initial go at moving into a proper packaged format ref #8

I think this is in line with what was being looked for. The result is on the PyPI test server [here](https://testpypi.python.org/pypi/PricesPaidGUI). The package is installable via 

```pip install -i https://testpypi.python.org/pypi pricespaidgui```

Unfortunately I don't have any familiarity with the project and haven't gone through and got it running, so I am not sure if this matches the structure that'd be needed. Any necessary packages needed for the package to run can be included via the install_requires array in setup.py.

To build a package, I'd recommend starting a new virtualenv, installing something like the following

```pip install -U "pip>=1.4" "setuptools>=0.9" "wheel>=0.21"```

and then running 

```python setup.py sdist bdist_wheel```

to generate the files. Form there they can be uploaded via command line or manually to PyPI. 

Let me know if this seems like the right direction.