QtIFW

Fix crash during install with latest SDK.

Since we can have a very big files, do not read them at all,
instead read chunks during hash verification. Avoids out of
memory exceptions. Fix notify(), if we catch an exception,
terminate the app as it's to late to do anything useful now.

Change-Id: I2805eeff7d8c62ea73264c92a764724e100840e3
Reviewed-by: Tim Jenssen <tim.jenssen@nokia.com>