Create JSONLayout.java

This Layout implementation depends on Apache Commons-Lang, Apache Logging Log4j 2, and Jackson 1.x.

Actual libraries I used for testing were:
 (Apache Logging) log4j-api-2.0-beta3.jar
 (Apache Logging) log4j-core-2.0-beta3.jar
 (Apache Commons) lang-2.4.2.jar
 (Codehaus Jackson) jackson-core-asl-1.9.11.jar