Install Shortcut for all users on Windows

[pherbel]

It seems installer create shortcut only for the current user, but the install directory is in the programfiles so it is available for all users.

Need to set this: SetShellVarContext for all (default is current)
in the https://github.com/trustcrypto/OnlyKey-App/blob/master/resources/windows/installer.nsi