log CONTRIBUTING @ 3429:1f0c290bd28a

age author description
2015-08-31 Kim Alvefur CONTRIBUTING: Run through pandoc to normalize markdown syntax
2015-08-31 Kim Alvefur CONTRIBUTING: Update guidelines and URL to hg repo
2015-04-09 Kim Alvefur Add README and CONTRIBUTING files containing the text from https://code.google.com/p/prosody-modules/