MXS-1300: Make output optional

Minor refactoring to the core library to allow multiple calls from within
the same program.

Added --quiet option to silence output so that tests aren't so
verbose. Currently this only works on UNIX based systems.

maxctrl/maxctrl.js

@@ -22,5 +22,5 @@ if (process.argv[0] == process.execPath) {
     process.argv.shift()
 }
 
-maxctrl(process.argv)
+maxctrl.execute(process.argv)
     .then(function(out) {}, function(out) {})