Fixed the dependencies
Created a test case class for current topic UI
Created a wireframe for current topic.
Created a test to refresh a topic
Progressing with a test to refresh current topic
Implemented a test for changing the current topic
Changed a test for current topic refresh to use an external server
TopicTrackerServlet now change the topic by POST request and notifies all the clients
Added logging when current topic changes
Change the current topic by a notification from Web Socket
Cleaned up servlet code
Added logback configuration
Configured logback to write to a file in /var/log directory
Fixed a problem with null TopicListener in tests
No topic is shown by default
Refactored TopicTrackerFactory and implemetations