[krbdev.mit.edu #5746] NIM: FEATURE: KRB5: Vista MSLSA synchronization

[Jeffrey Altman via RT]

On Vista, the MSLSA is a read/write credentials cache.

Synchronize the default identity into the MSLSA ccache each time the 
identity changes or the identity credential is renewed.

Copy logon credentials from the MSLSA to an API ccache if they do not
already exist.

Provide a configuration option to enable/disable this behavior.