Add pagination configuration
Add initial nextPage/eachPage implementation
Add integration tests for various paginated services
Add support for more complex pagination configuration, adds integration tests for S3
Add jamespath support
Refactor nextPage implementation to use jamespath expressions
Update pagination configuration
Add extra pagination configuration
Fix eachItem iteration
Add wildcard support in jamespath expressions
Add documentation for pagination methods
Add experimental pagination support

Adds the following methods:

* Request.eachPage(callback)
* Request.eachItem(callback)
* Request.isPageable()
* Response.nextPage(callback)
* Response.hasNextPage()

Example iteration over S3 objects:

```js
s3.listObjects(params).eachPage(function (err, data) {
  console.log(data); // logs each individual page of data
});
```

A response object can also use nextPage() to get the next page:

```js
s3.listObjects(params, function (err, page1) {
  // got first page
  this.nextPage(function (err, page2) {
    // this will contain the second page of data
  });
})
```

When no more pages are present, null is passed as data to the callback.