Add setup.py to allow install using pip

adding a setup.py would allow this package to be installed using [pip](https://python-packaging-user-guide.readthedocs.org/en/latest/projects.html#pip), like so:

        $ pip install git+git://github.com/jotform/jotform-api-python.git

Or:

        $ cat requirements.txt
        django==1.6.5
        jotform>=1.0,<2.0
        stripe>=1.18.0,<1.19.0
        $ pip install -r requirements.txt

Having a setup.py in your package would also be the first step toward getting this package registered on https://pypi.python.org/pypi , allowing your package to be installed as easy as:

        $ pip install jotform