Added a notification when an agent disconnects during configuration.
For example, if someone runs their app with the javaagent flag, CodePulse shows its "an agent has connected" message and starts waiting for the user to acknowledge it. Then the user kills the application instead of acknowledging it (i.e. Ctrl+C). The connection looper will return to an Idle state and wait for a new connection, and CodePulse will display a notification stating that "the agent has disconnected".