Silence Ractive debug messages

[timoxley]

This silences the debug text that Ractive prints to the console. Prevents messy webpack build terminal output.

Since updating to Ractive 0.8.0, webpack builds are trashed by ractive's debug messages:

# building clientside application
node --max-old-space-size=4096 `which webpack` --output-path dist/build -d --watch --progress --color
 42% 28/52 build modules%cRactive.js %c0.8.0 %cin debug mode, %cmore... color: rgb(114, 157, 52); font-weight: normal; color: rgb(85, 85, 85); font-weight: normal; color: rgb(85, 85, 85); font-weight: normal; color: rgb(82, 140, 224); font-weight: normal; text-decoration: underline;
You're running Ractive 0.8.0 in debug mode - messages will be printed to the console to help you fix problems and optimise your application.

To disable debug mode, add this line at the start of your app:
  Ractive.DEBUG = false;

To disable debug mode when your app is minified, add this snippet:
  Ractive.DEBUG = /unminified/.test(function(){/*unminified*/});

Get help and support:
  http://docs.ractivejs.org
  http://stackoverflow.com/questions/tagged/ractivejs
  http://groups.google.com/forum/#!forum/ractive-js
  http://twitter.com/ractivejs

Found a bug? Raise an issue:
  https://github.com/ractivejs/ractive/issues


%cRactive.js: %cUnqualified method events are deprecated. Prefix methods with '@this.' to call methods on the current Ractive instance. color: rgb(114, 157, 52); color: rgb(85, 85, 85);
 59% 373/451 build modules%cRactive.js: %cProxy events with arguments are deprecated. You can fire events with arguments using "@this.fire('eventName', arg1, arg2, ...)". color: rgb(114, 157, 52); color: rgb(85, 85, 85);

Ideally this would be an option passed into the loader, but this is a good start.