Implement include/exclude functionality

This pull request implements include and exclude functionality as described in man 5 rsyncd.conf.

I found a use for it recently when I needed to only allow certain files to be visible in a rsync module.

Initially I had a concern with `include` causing issues, as it's sort of a "reserved word" in puppet, but all the tests pass for me, and I've implemented this in a test environment on CentOS 6.2.

Tested with puppet-server on Ubuntu 10.04 LTS and puppet-agent on CentOS 6.2. Both 32 bit. Specs pass using the dependencies in `.gemfile`

Thoughts?