move pb to package

This also moves config loading to XDG_CONFIG_DIRS.
add testing skeleton

gitignore the tox and distutils cruft; more better requirements.txt.
update deployment documentation

We might also consider suggesting installing pb itself into the virtual
environment.
add app factory; move instantiation to wsgi stub

This feels like slightly less of a hack--also should make testing less
dirty.
convert README.md to reStructuredText
move varnish to docs; convert to reStructuredText
add initial test coverage
Merge pull request #82 from buhman/tests

test automation