Move static web resources to / instead of under the rootCap.

Note that we are now using host-relative URLs and can no longer be
transparently reverse-proxied to have a subdirectory for a public
URL. This should be fixed by having all the "/client/..." URLs
be either "client/..." or "../client/" depending on the config,
by way of them being derived from index.html and that becoming
a template.
All modules get uniform __future__ decls.
Move main.py effects into a function.

This is in preparation for having a setup.py; apparently the mechanism
for generating binaries will invoke a function, but not emulate
"python -m ...".

Also remove stray unused import of gnuradio.eng_option.
__builtins__ "is an implementation detail" and varies, use __builtin__
Add setup.py and MANIFEST.in for project packaging.