Add debian packaging

Auto configure PAM with pam-auth-update:
  - enable ccreds-check ccreds-save
  - enable krb5

debian/postinst

@@ -0,0 +1,32 @@
+#!/bin/sh
+set -e
+
+case "$1" in
+    configure)
+        # Configure PAM for credential cache 
+        apt-mark manual libpam-ccreds >/dev/null || true
+        if [ -e /usr/share/pam-configs/ccreds-check ] ; then
+            pam-auth-update --force --package --enable \
+                ccreds-check ccreds-save || true
+        fi
+        # Configure PAM for Kerberos
+        if [ -e /usr/share/pam-configs/krb5 ] ; then
+            pam-auth-update --force --package --enable krb5 || true
+        fi
+    ;;
+
+    abort-upgrade|abort-remove|abort-deconfigure)
+    ;;
+
+    *)
+        echo "postinst called with unknown argument \`$1'" >&2
+        exit 1
+    ;;
+esac
+
+# dh_installdeb will replace this with shell code automatically
+# generated by other debhelper scripts.
+
+#DEBHELPER#
+
+exit 0