fix guest additions not being installed on ubuntu 11.04 i386

the guest additions were failing to install because the proper
`linux-headers-VER-generic` package was being installed after
the guest additions but the guest additions needed that package.

resolved by moving the package install before the guest
additions install.

templates/ubuntu-11.04-server-i386/postinstall.sh

@@ -2,6 +2,14 @@
 
 date > /etc/vagrant_box_build_time
 
+# Apt-install various things necessary for Ruby, guest additions,
+# etc., and remove optional things to trim down the machine.
+apt-get -y update
+apt-get -y upgrade
+apt-get -y install linux-headers-$(uname -r) build-essential
+apt-get -y install zlib1g-dev libssl-dev libreadline5-dev
+apt-get clean
+
 # Installing the virtualbox guest additions
 apt-get -y install dkms
 VBOX_VERSION=$(cat /home/vagrant/.vbox_version)
@@ -13,14 +21,6 @@ umount /mnt
 
 rm VBoxGuestAdditions_$VBOX_VERSION.iso
 
-# Apt-install various things necessary for Ruby, guest additions,
-# etc., and remove optional things to trim down the machine.
-apt-get -y update
-apt-get -y upgrade
-apt-get -y install linux-headers-$(uname -r) build-essential
-apt-get -y install zlib1g-dev libssl-dev libreadline5-dev
-apt-get clean
-
 # Setup sudo to allow no-password sudo for "admin"
 cp /etc/sudoers /etc/sudoers.orig
 sed -i -e '/Defaults\s\+env_reset/a Defaults\texempt_group=admin' /etc/sudoers