Kerberos SSO Update

When going back from SSO to database mode, SSO was still
being attempted. Code was looking at the wrong configuration
variable for authentication mode.
Merge pull request #747 from abellotti/single_signon_update

Kerberos SSO Update
Add support for Version 5 XFS filesystems

This includes adding CRC fields to several on-disk
data structures including directory headers, as
well as allowing for a filetype field in the directory
entries.

Rubocop warnings in the code were fixed as well as
style issues pointed out by reviewers.