[SSSD] [PATCH] Select principal for GSSAPI authentication

[Jan Zelený]

I'm sending two patches solving selection of appropriate principal for GSSAPI 
authentication from keytab file.

A part of the first patch is a fix of an error present in the documentation. I 
did that early in the development phase of the patch and I didn't want to 
tamper with the finished patch any more. Sorry for this inconsistency.

Jan