Consolidate communication channels

[wikimatze]

Based on padrino/padrino-framework#1769:

• mailing lis: Not widely used, messages get lost and long response time
• irc #padrino channel: More people are there and newbies asking questions which did not get answered within minutes will probably never go there again since they don't get instant feedback. Since we are still a small group, we can find always the time to answer the questions like @dariocravero said above
• reddit channel: I contacted the author to give me access to the channel => it would be good to share blog post and articles written about Padrino
• stackoverflow: Didn't know that it exists
• own Q & A system: I set a possible solution up under my webspace.
• padrinorb.org: Official page, much of the documentation is outdated but RailsGirls are working for a solution about how to make it up to date.
• padrinobook.com: A book about how to use and run Padrino

Make a clear link where people can get help and where they can post things and ask questions as well.