Add GUI interface to select ROS master

[mathemaphysics]

This is the story which will add a settings panel to LiDARShooterGUI containing the ROS master host and port which can be updated by the user.

Acceptance Criteria:

1. A new settings panel exists and contains at least a tab or block which displays the current (default) ROS master in a text field
2. Beneath the ROS master field in the settings panel should be an Update button and an error field which can display the return status of a call to update the master and also potentially live URL analysis to indicate a badly formatted URL
3. Bonus: Create a configuration file to LiDARShooterGUI which will contains the default ROS master (just localhost unless otherwise needed)