added two functions for batch operations

The function names are:
_sendBatchRequest and _sendBatchRequest_v3
Added conditions to handle batch operations.
Added two new const variables for use with batch operations.
Added a new case for batch operation

new case in switch condition of function _parseIDS_v3.
Create example_customer_add_batch.php
IPPv3 Batch operation example

Add multiple customers in single request instead of multiple request.
Batch Request Service
Batch Request Object
BatchItemRequest object
BatchItemResponse Object
Merge https://github.com/WAS33M/quickbooks-php

Conflicts:
	QuickBooks/IPP.php
	QuickBooks/IPP/Parser.php

imported branch capabilitios from https://github.com/consolibyte/quickbooks-php/pull/18.patch