Add setup.py, resolve name shadowing

[clbarnes]

• Adding a setup.py allows others to use the ResnetBuilder in a more tidy and traceable way.
• Variables called input were renamed to input_data to resolve name clashes with the builtin input

Versioning is left up to @raghakot

[Dario-Mantegazza]

I've managed to install your version with pip install git+https://github.com/clbarnes/keras-resnet.git@clbarnes-dev