There was no way to customize help pages for config files. Added optional
`HELP` variable to `.def` files.


git-svn-id: file:///var/svn/freetz/trunk@10028 149334a1-2f27-0410-a3b9-fc62619ac1e6
remove_mediasrv: remove mediasrv webif settings (refs #1391)

git-svn-id: file:///var/svn/freetz/trunk@10029 149334a1-2f27-0410-a3b9-fc62619ac1e6