v0.41.0

Primary changes:

• #309, GC logger now uses powers of 1024 to match command line options to JDK.
• #316, Use compile scope in POM for dependencies exposed in public API.
• #317, Move placeholder ids to separate sub-project and deprecate.
• #318, Add spectator-web-spring sub-project for exposing data in the registry.

A comprehensive list of changes can be found in the commit log: v0.40.0...v0.41.0