[AQUA] Better error codes for AQUA API

[ben_rightscale]

If you use an invalid field in an AQuA query, the error is "There is a syntax error in one of the queries in the AQuA input". This is significantly less useful than the SOAP API, which actually tells you which field is invalid. SOAP example:

...
<zns:queryString>select AccountingCode, AppliedToInvoiceItemId, ChargeAmount, ChargeDate, ChargeName, CreatedById, CreatedDate, Id, ProcessingType, Quantity, RevRecStartDate, ServiceEndDate, ServiceStartDate, SKU, SubscriptionId, TaxAmount, TaxCode, TaxExemptAmount, TaxMode, UnitPrice, UOM, UpdatedById, UpdatedDate, InvoiceId, ChargeId, ProductId, ProductRatePlanChargeId, RatePlanChargeId from InvoiceItem</zns:queryString> 
</zns:query> 
...

SOAP response (status 500): 

...  invalid field for query: InvoiceItem.productrateplanchargeid ...

[chris]

Thanks for raising, Ben. We'll take a look at this.