Windows: disable short names on Win7 and 2008 R2

Windows: disable short names on Win7 and 2008 R2

After listening to a presentation from Microsoft's file system
team and speaking with anti-virus vendors, it is not only safe
to disable ShortNames on non-boot volumes in Win7 and 2008 R2
but it is a definite win for performance, stability and security
of the system.

Change-Id: I706a8a17b0ae76189aeebaf254c8c70739d12f09
Reviewed-on: http://gerrit.openafs.org/7989
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
Tested-by: Jeffrey Altman <jaltman@your-file-system.com>