Put devstack-version info into separate file

As a follow on to I4c269a7f3d63ee9a976e7c3636fc3e5e8dab9ae3; the
quoting gets tricky when putting arbitrary command-substitution
strings into saved echo-able strings.  As they say, "the only winning
move is not to play" :)

An alternative proposal is to not write this into a script but just
dump info into a file.  To my mind, this has several advantages --
avoid getting involved in quoting, not dropping a script into the
global environment -- it's just as easy to "cat" -- and the plain-text
file can be collected as an artifact during log collection (also moved
git commit line to separate line for easier parsing during log search,
etc).

Change-Id: Ic7391dd087657c0daf74046e4a052c53f4eb6e1a
diff --git a/functions b/functions
index f04bc1f..6f2164a 100644
--- a/functions
+++ b/functions
@@ -750,19 +750,16 @@
     echo $port
 }
 
-
+# Save some state information
+#
+# Write out various useful state information to /etc/devstack-version
 function write_devstack_version {
-    pushd $TOP_DIR
-    local git_version=""
-    git_version=$(git log --format="%H %ci" -1)
     cat - > /tmp/devstack-version <<EOF
-#!/bin/bash
-
-echo "DevStack Version: ${DEVSTACK_SERIES} - ${git_version}"
-echo "OS Version: ${os_VENDOR} ${os_RELEASE} ${os_CODENAME}"
-
+DevStack Version: ${DEVSTACK_SERIES}
+Change: $(git log --format="%H %s %ci" -1)
+OS Version: ${os_VENDOR} ${os_RELEASE} ${os_CODENAME}
 EOF
-    sudo install -m 755 /tmp/devstack-version /usr/local/bin/devstack-version
+    sudo install -m 644 /tmp/devstack-version /etc/devstack-version
     rm /tmp/devstack-version
 }