Add Debian/Ubuntu installation instructions
Add Debian/Ubuntu installation instructions

calleerlandsson/pick,prahlad37/pick,DBOTW/pick,prahlad37/pick,prahlad37/pick,prahlad37/pick,thoughtbot/pick,thoughtbot/pick,thoughtbot/pick,calleerlandsson/pick,DBOTW/pick,thoughtbot/pick,DBOTW/pick,calleerlandsson/pick