A couple of ruby one-liners for dumping out the content of a github commit hook payload:
For hooks that use type application/json:
$ ruby -rpp -rjson -rsinatra -e 'set :port, 8000; post "/*" do; pp JSON(request.body.read); end'
For hooks that use type application/x-www-form-urlencoded:
$ ruby -rpp -rjson -rsinatra -e 'set :port, 8000; post "/*" do; pp JSON(params[:payload]); end'
Will writes 