Simple repair of broken resubscribe. Easy fix, but still needs testing.

Fixes #3

Author: forresthopkinsa

lib/src/main/java/ua/naiksoftware/stomp/client/StompClient.java

@@ -289,6 +289,7 @@ private Completable subscribePath(String destinationPath, @Nullable List<StompHe
 
     private Completable unsubscribePath(String dest) {
         mStreamMap.remove(dest);
+        mTopics.remove(dest);
 
         String topicId = mTopics.get(dest);
         Log.d(TAG, "Unsubscribe path: " + dest + " id: " + topicId);