SimpleRevisionServer refactor + Minor cleanup

Does several small things:

 * Moves SimpleRevisionServer into its own package.
 * Adds unit tests around SimpleRevisionServer's behavior. 
 * Uses immutable maps in a few places where we were using static initialization blocks.
 * Changes the naming of classes (`My*`) to distinguish from convention for documentation examples.
 * Cleans up the imports.
 * Minor tweaks to use of generics. 
 * Reducing the visibility of member variables to `private` where appropriate.