Improved client and reseller limit checks

Fixed: FS#810 - FTP - If username is left blank and client clicks options a clientname_ blank username is created.

- Updated the user and database prefixes to use this storage.

Removed server selector from FTP- and Shell-User forms, as the server is always identical with the server ID of the selected website.

Added chroot options to the shell user form
Added jailkit ini settings
Added ini settings for fastcgi
Fixed bug with web delete not removing parent web user unless that was intentional ?
Changed name of shell user plugin so plugin order calls this first
Started a change to the update script.

TODO: Fix problem with jailkit chroot users logging into parent web user's directory. Fixup bash command prompt to display the correct user somehow because they all share the same id. 

Fixup install / update script so the fastcgi script and directory is created for the ispconfig site on setup / update. Can't work out how to get to the templating system to generate the script from. 

- Changed shell of website linux user to /bin/false

Updated apache ssl cert creation.