A few updates

- Ignoring PHPStorm IDE project folder
- Fixing XML_DROP constant error in SalesOrder object
Adding method "addSalesOrderLine" to SalesOrder.php
Merge branch 'refs/heads/hotfix/so' into develop
Fixing bug in setAmount for SalesOrderLine.php
Merge branch 'refs/heads/hotfix/so' into develop
SalesOrder asQBXML signature matches Object now
Merge branch 'refs/heads/hotfix/so' into develop
Fixing SalesOrder methods
Merge branch 'refs/heads/hotfix/so' into develop
Fixing object() on SalesOrderLine.php
Merge branch 'refs/heads/hotfix/so' into develop
Adding type of request for line items
Merge branch 'refs/heads/hotfix/so' into develop
Fixing a bug in QBXML Invoice
Merge branch 'refs/heads/hotfix/so' into develop
Fixing the request type on SalesOrder
Merge branch 'refs/heads/hotfix/so' into develop
Fixing SalesOrder to include correct "SalesOrderLineAdd"
Merge branch 'refs/heads/hotfix/so' into develop
Help for debugging