[horde] autodetect webroot

[Patrick Boutilier]

Per olof Ljungmark wrote:
> Upgrading from Horde 3.1.3 to 3.1.4
> 
> I had to manually enter
> 'webroot' => '',
> in registry.php to get it to work using
> http://webmail.example.com
> instead of
> http://webmail.example.com/horde
> with all necessary changes applied to httpd.conf and config/conf.php
> 
> Is autodetect supposed to work? Could not find any bugs relating to it.

autodetect of a '' webroot didn't work here either. Did not investigate 
why, just manually set to ''