Fix up deleteFile() so that it never fails.
Fix up deleteFile() so that it never fails.

And also so that tests wait for it before continuing to the next one.

polyvi/xface-mobile-spec,polyvi/xface-mobile-spec,lorinbeer/cordova-mobile-spec,ollie314/cordova-mobile-spec,ollie314/cordova-mobile-spec,apache/cordova-mobile-spec,polyvi/xface-mobile-spec,apache/cordova-mobile-spec,corimf/cordova-mobile-spec,apache/cordova-mobile-spec,ollie314/cordova-mobile-spec,apache/cordova-mobile-spec,ollie314/cordova-mobile-spec,ollie314/cordova-mobile-spec,corimf/cordova-mobile-spec,apache/cordova-mobile-spec,corimf/cordova-mobile-spec,corimf/cordova-mobile-spec,corimf/cordova-mobile-spec