It's a little confusing having both a "supporter" and "supporters" app. This is
a fairly minor change to move the sustainer banner urls/views into the existing
"supporters" app. The functionality isn't directly related, but it is all about
sustainers.
Having Python code in "conservancy/static" is a bit suprising to people familiar
with Django. The name "static" is usually reserved for assets like CSS, JS and
images.
I'm moving `conservancy/static/views.py` to `conservancy/views.py` and removing
`conservancy/static/__init__.py`.