Static files are now under a directory in xdg directories (config or cache)

New paths:
$XDG_CONFIG/packages.conf
$XDG_CONFIG/sendmail.conf
$XDG_CACHE/packages.conf

Allow upstream web parsing to be retryed in case of error. The number of retry
can be set with the retry parameter.

- rename config example files
- remove __init__.py from /usr/bin
- install README.rst and example*.conf in doc directory
- ship misc file into dist tarball