Add batch support

[daffl]

It should be pretty easy to add general support for feathers-batch to batch service calls. A small change that can add a big performance improvement to applications.

Batching can be done manually like:

var app = feathers('http://todos.feathersjs.com')
  .configure(feathers.jquery());

// Set all batching calls to execute in series
app.batch('type', 'series');

app.batch.start();

todoService.create({
  text: 'A todo',
  complete: false
}, function(error, todo) {
  console.log('Success');
});

todoService.find(function(error, todos) {
  console.log('Got the following Todos', todos);
});

app.batch.stop();

Or with a timeout that collects all simultaneous requests sent within a certain interval:

var app = feathers('http://todos.feathersjs.com')
  .configure(feathers.jquery());

app.batch({
  type: 'series',
  timeout: 100 // batch all request within 100ms
});

todoService.create({
  text: 'A todo',
  complete: false
}, function(error, todo) {
  console.log('Success');
});

todoService.find(function(error, todos) {
  console.log('Got the following Todos', todos);
});

[daffl]

I'm going to close this. It will be added when with the final version of the batch plugin when we add a performance and scaling chapter to the documentation.