Fix "brctl: invalid command" message appearing in startup logs

We were actually failing to call brctl in configure-vm.sh. I finally
tracked it down to the attempt to delete the docker0 bridge. This
particular package was getting installed later by Salt anyways, so
all this PR is doing is moving the package install up from Salt to
bash.

Also adds some minor logging.

cluster/gce/configure-vm.sh

@@ -83,10 +83,18 @@ for k,v in yaml.load(sys.stdin).iteritems():
 }
 
 function remove-docker-artifacts() {
+  echo "== Deleting docker0 =="
+  # Forcibly install bridge-utils (options borrowed from Salt logs).
+  until apt-get -q -y -o DPkg::Options::=--force-confold -o DPkg::Options::=--force-confdef install bridge-utils; do
+    echo "== install of bridge-utils failed, retrying =="
+    sleep 5
+  done
+
   # Remove docker artifacts on minion nodes, if present
   iptables -t nat -F || true
   ifconfig docker0 down || true
   brctl delbr docker0 || true
+  echo "== Finished deleting docker0 =="
 }
 
 # Retry a download until we get it.
@@ -152,6 +160,9 @@ EOF
   done
 
   rm /usr/sbin/policy-rc.d
+
+  # Log a timestamp
+  echo "== Finished installing Salt =="
 }
 
 # Ensure salt-minion never runs
@@ -352,6 +363,7 @@ function configure-salt() {
 }
 
 function run-salt() {
+  echo "== Calling Salt =="
   salt-call --local state.highstate || true
 }