SLING-2024 - Replace file logger with logback

Updated the readme to reflect current state

git-svn-id: https://svn.apache.org/repos/asf/sling/trunk@1542962 13f79535-47bb-0310-9956-ffa450edef68
SLING-2024 - Replace file logger with logback

Renamed to README.md file

git-svn-id: https://svn.apache.org/repos/asf/sling/trunk@1542963 13f79535-47bb-0310-9956-ffa450edef68