RADIUS secret in file

Attached is the "last step" of the RADIUS authenticaiton as I promised
Stephen - which allows the reading of the RAIDUS secret from a file
instead of hardcoded in pg_hba.conf. One reason being you don't want
the secret in your config file that may be in a shared repository or
such. IIRC Stephen had some other reason, but I'll leave it to him to
fill that in :-)


-- 
 Magnus Hagander
 Me: http://www.hagander.net/
 Work: http://www.redpill-linpro.com/