QtIFW

Implement shared class for binary content.

Fixes binary content destructor. Makes sure we unregister
and clear the embedded resources only once. Helps to avoid
instantiating several copies of BinaryFormatEngineHandler.
Implement some statics to read and register the binary content.

Change-Id: If7c72fe7c1588497736552f9c3490f58484b602e
Reviewed-by: Tim Jenssen <tim.jenssen@nokia.com>
Reviewed-by: Niels Weber <niels.2.weber@nokia.com>