smartd: added smartd.conf Directives -T and -s. The -T Directive

enables/disables Automatic Offline Testing.  The -s Directive
enables/disables Attribute Autosave. Documentation and
example configuration file updated to agree.

Some revision of documentation to clarify the different between offline
testing and self-testing.


git-svn-id: https://smartmontools.svn.sourceforge.net/svnroot/smartmontools/trunk@310 4ea69e1a-61f1-4043-bf83-b5c94c648137