added an option to replace built in server.inject

So you can now call the plugin with the replace option
```javascript 
server = new Hapi.Server();
      server.pack.register({
        plugin: require('./'),
        options: {
          replace: true
        }
      }, done);
      server.route({
        path: '/test',
        method: 'GET',
        handler: function (request, reply) {
          reply('hello');
        }
      });
```
and you can just use server.inject for your promises (and you can still use it with regular callback)