Add a call to upgrade zx to the end of installation

install_unix

@@ -4,6 +4,13 @@ if escript_path=$(command -v escript)
   then
     echo "Using escript found at $escript_path"
     escript install.escript
+    if zx_link=$(command -v zx)
+      then
+        echo "zx found in \$PATH at $zx_link. Checking for upgrade."
+        zx upgrade
+      else
+        echo "zx is not yet in \$PATH. Once you have added zx's location to \$PATH run \`zx upgrade\`."
+    fi
   else
     echo "Could not locate an Erlang installation."
 fi