Don't install vim or locate by default

Devstack doesn't need vim or locate, if someone wants to use them, they
can just install them afterwards.

Change-Id: I00f27c20c86d89465e4aefc67ed645a309c09a03
diff --git a/tools/xen/prepare_guest.sh b/tools/xen/prepare_guest.sh
index 440774e..2b5e418 100755
--- a/tools/xen/prepare_guest.sh
+++ b/tools/xen/prepare_guest.sh
@@ -73,7 +73,7 @@
 # Install basics
 apt-get update
 apt-get install -y cracklib-runtime curl wget ssh openssh-server tcpdump ethtool
-apt-get install -y curl wget ssh openssh-server python-pip git vim-nox sudo python-netaddr
+apt-get install -y curl wget ssh openssh-server python-pip git sudo python-netaddr
 pip install xenapi
 
 # Install XenServer guest utilities