ENYO-3506: correcting cancelation on getFiles

Removed AJAX cancelation as this is not an AJAX operation. The operation being i/o, we don't want to crash it. We let it complete and use a flag for abortion.
ENYO-3506 correcting last step submitBuildRequest

The cancelation stops AJAX in flight, _and_ raise the error at async.waterfall level to stop the process.