dillon1000/react

Flip console.warn to use warning module so users can intercept all warnings by shimming the warning module.

The two remaining console.warns are:

/Users/jsproch/react/src/test/mock-modules.js:
   19      return mocks.generateFromMetadata(mocks.getMetadata(exports));
   20    } catch (err) {
   21:     console.warn(err);
   22      return exports;
   23    }

/Users/jsproch/react/src/vendor/core/warning.js:
   39        var argIndex = 0;
   40        var message = 'Warning: ' + format.replace(/%s/g, () => args[argIndex++]);
   41:       console.warn(message);
   42        try {
   43          // --- Welcome to debugging React ---