Merge proxy and router/weaver processes.

Note: we no longer need to detect awsvpc when launching.
The "AWS VPC" mode is now set via the `--awsvpc` flag.
Before we had to "detect" it when the proxy was potentially started
later, after the router had started.

We drop WEAVEPROXY_DOCKER_ARGS as obsolete.

test/config.sh

@@ -136,7 +136,7 @@ stop_weave_on() {
     host=$1
     weave_on $host stop 1>/dev/null 2>&1 || true
     if [ -n "$COVERAGE" ]; then
-        for C in weaveplugin weaveproxy weave ; do
+        for C in weaveplugin weave ; do
             collect_coverage $host $C
         done
     fi