A bit more debug output PaypalPro IPN

I recently had to delve into PaypalPro IPN & in the process added a little more info to the debug output which I thought would be handy in CORE. - patch attached.

Interestingly the problem I had was that some recurring contributions were imported from one Civi DB to another & the contribution IDs & recurring IDs had changed so I had to hack our install to look up these numbers based on matching the invoice number rather use the ones from the paypal IPN. Pretty edge stuff but I would have thought looking up based on the invoice number would make more sense in general (that's just an aside - the patch just adds values to the debug output)