[proxy] Autoconfigure TLS based on daemon settings

With this on OSX you can:
```sh
$ boot2docker init
$ boot2docker up
$ eval $(boot2docker shellinit)
$ weave launch
$ eval $(weave env)
```

.gitignore

@@ -40,6 +40,7 @@ prog/weaveproxy/weaveproxy
 prog/sigproxy/sigproxy
 prog/weavewait/weavewait
 prog/netcheck/netcheck
+prog/docker_tls_args/docker_tls_args
 testing/cover/cover
 testing/runner/runner
 tools/bin
@@ -55,6 +56,7 @@ prog/weaveexec/weaveproxy
 prog/weaveexec/weavewait
 prog/weaveexec/sigproxy
 prog/weaveexec/netcheck
+prog/weaveexec/docker_tls_args
 prog/weaveexec/docker*.tgz
 Vagrantfile.local
 test/tls/*.pem