- Update installation on Squeeze

Updated jailkit instalation procedures to install jailkit as debian package. Because it´s better to remove and update. And because jailkit is debianized.
Install debian package is better then pure source.

Modified the update scripts to check if a download of the tar.gz has succeeded.

Fixed a bug that prevented the modification of website settings of a site that the user created.

- The home directory of a shell user gets deleted when the user is deleted.