Conflict with ngcp-system-tools-* packages

The change from svn r10685 is incomplete, causing the upgrade to fail:

| Unpacking replacement kamailio ...
| dpkg: error processing /var/cache/apt/archives/kamailio_3.3+ngcp2.6.3_amd64.deb (--unpack):
|  trying to overwrite '/etc/init.d/kamailio-proxy', which is also in package ngcp-system-tools-ce 0.4.5

Needs review, testing + release (branch/tag + release-2.6-update) by Jon.

From: Michael Prokop <mprokop@sipwise.com>

pkg/kamailio/deb/squeeze/control

@@ -43,6 +43,9 @@ Package: kamailio
 Architecture: any
 Depends: adduser, ${misc:Depends}, ${shlibs:Depends}
 Conflicts: kamailio-regex-modules
+Conflicts: kamailio-regex-modules,
+           ngcp-system-tools-ce (<< 0.6.0),
+           ngcp-system-tools-pro (<< 0.6.0)
 Suggests: kamailio-berkeley-modules,
           kamailio-carrierroute-modules,
           kamailio-cpl-modules,