initial prep for client state persistence

.gitignore

@@ -16,3 +16,4 @@
 bin/
 *.snap
 windscribe-proxy
+wndstate.json

wndclient/wndclient.go

@@ -75,7 +75,7 @@ type WndClient struct {
 	Status             int
 	UserID             string
 	SessionAuthHash    string
-	Mux                sync.Mutex
+	Mux                sync.Mutex `json:"-"`
 	ProxyUsername      string
 	ProxyPassword      string
 }