Add a make task to sign the 64bit driver

64bit Windows requires that drivers are signed. Unfortunately I don't
have a valid signing certificate, so I'm self signing the certificates.
Run "make sign" to self sign the 64bit driver.

To use a self signed driver you need to enable test signing.
Run "bcedit -set TESTSIGNING ON" as administrator.
Add versioning to the install process

This came about because I had an earlier version of the registry key
installed, and the installer wouldn't create the correct one. That of
course, caused the driver to not load. There is now a new "Version"
value in the registry that the install script can check against. It is
directly on the kblayout key, indicating that I might want to move
"Selected Layout" there.