add 'at' to prerequsite list

debian/control

@@ -7,7 +7,7 @@ Standards-Version: 3.6.1
 
 Package: openvpn-server
 Architecture: all
-Depends: openvpn, openssl, nsis (>= 2.06-4), zip, ucf, ${misc:Depends}, bc, cryptsetup, ifstat, bsd-mailx, sharutils, bash-completion
+Depends: openvpn, openssl, nsis (>= 2.06-4), zip, ucf, ${misc:Depends}, bc, cryptsetup, ifstat, bsd-mailx, sharutils, bash-completion, at
 Description: A system to assist the management of OpenVPN servers
  Provides a simplified OpenVPN server configuration at installation time,
  and a set of scripts to automatically create Windows and Linux client