Changes to make this run in OpenShift 3

[gregswift]

For the most part I've got this running in OpenShift 3 using python 3.5 s2i.

• icanhaz.py was not executable, so I updated that here
• Upon trying to run icanhaz.py dependencies (flask) were missing and it will process a requirements.txt so I added one
• Figure out how to configure bind using --host=0.0.0.0 See next item:
• Decided to let gunicorn handle the serving and binding for openshift, so added to requirements.
  ** Had to set APP_MODULE environment variable in Deployment config to icanhaz:app (not represented here)
• Add support for X-Fordwarded-For headers for running behind lb/proxy

Because icanhaz* requires system level packages, to get to fully featured it would likely require a custom Docker image. I didn't actually try running the existing version of this image.

[gregswift]

@major would it help if I made the proxy fronting support a feature flag? I can definitely see why you wouldnt want it on your implementation