The directory nesting is unnecessary here and confusing to navigate. I've moved
all apps to the project subdirectory, currently called "www", but soon to be
renamed "conservancy".
I've also moved manage.py to the top-level directory.
With a valid URL, a past donor can upgrade to a supporter by donating
the rest of the amount. Django validates the data and, if it passes,
puts it in the form. The JavaScript does most of the work from there.
