Add contributors file
Add contributors file

Signed-off-by: Daniel Farina <bee449cdf8304c08319f4f5bbfe9582c670af7b4@acm.org>

ajmarks/wal-e,alex/wal-e,modulexcite/wal-e,x86Labs/wal-e,ArtemZ/wal-e,DataDog/wal-e,intoximeters/wal-e,heroku/wal-e,tenstartups/wal-e,RichardKnop/wal-e,fdr/wal-e,nagual13/wal-e,fdr/heroku-wal-e,wal-e/wal-e,equa/wal-e