Changes to IOTests per review, plus other improvements
Changes to IOTests per review, plus other improvements

Add path to assertion messages to pinpoint test case on failures.

duplicati/duplicati,duplicati/duplicati,mnaiman/duplicati,duplicati/duplicati,mnaiman/duplicati,mnaiman/duplicati,duplicati/duplicati,duplicati/duplicati,mnaiman/duplicati,mnaiman/duplicati