Move updater class into sdk binary and rename to UpdateChecker.

Remove some now superfluous methods from binary format.
Adjust initializing some objects as we need them not earlier.
Unify implementation of accessing the right binary to read the
content from.
UpdateChecker does now have its own run checker, makes it possible
to run the binary even if a e.g. maintenace tool is already running.

Change-Id: I94f32f7f38b62b5aee433753abc2fe72e879ddc9
Reviewed-by: Niels Weber <niels.weber@digia.com>
Reviewed-by: Kai Koehne <kai.koehne@digia.com>