add a couple more packages

Signed-off-by: Robert Nelson <robertcnelson@gmail.com>

scripts/squeeze-preseed.cfg

@@ -1,3 +1,10 @@
+# Individual additional packages to install
+d-i pkgsel/include string uboot-mkimage pastebinit
+
+# Whether to upgrade packages after debootstrap.
+# Allowed values: none, safe-upgrade, full-upgrade
+d-i pkgsel/upgrade select safe-upgrade
+
 # Controls whether to use NTP to set the clock during the install
 d-i clock-setup/ntp boolean true