Use the server port in DOKU_COOKIE when securecookie is defined FS#1664

Ignore-this: de9ef30fc53fbfc1caa74b55f97290a5

This should avoid problems on portbased virtual hosts.
This patch might log you out ;-)

darcs-hash:20090801222159-7ad00-808a91dd29af758ef10d7942888c2c22d8b8b888.gz