code: function(name, fn) {
      if (name == null || fn == null) return;
      generatorStore[name] = function() {
          var args = [].slice.call(arguments);
          return function() {
              return fn.apply(fn, args);
          };
      };
  }
docs: Creates and stores a new generator function from a data provider. A data
  provider is basically a function that returns some data. Generators wrap
  data providers and pass any parameters they receive.
  
  Params:
  - name: the name of the generator, as a string
  - fn: the provider function
  
  Examples:
  >>> fakery.generator('now', function() {
  return new Date();
  });
  // => undefined