Auto meta descriptions not prefferable

[tablatronix]

Add option to disable meta desc from content excerpts.

Fixes issues like this.
http://get-simple.info/forums/showthread.php?tid=4845&pid=37303#pid37303
and
#347

[tablatronix]

👍 for defaulting to NO auto desc with option to restore ( old functionality )

[cnb]

👍 same as tablatronix

[RenXXX]

👍 as proposed default to NO

[tablatronix]

# Enable auto meta descriptions from content excerpts when missing
# define('GSAUTOMETAD',true);