Fix "ruby_interact.rb" to "ruby_interact.pd"
'compute audio' is now 'PSD' in PD

As per: https://twitter.com/marmitejunction/status/323003993976614912
Add '-I.' to make requires from 'lib' work
Ignore "config.yml" (keep secrets secret! :-)
Add '-I.' to make requires from 'lib' work

(forgot this on in fdee678)
Merge pull request #2 from pvdb/docu_updates

Documentation updates to README