update site plugin version to fix AetherClassNotFound error when building site with maven 3.2.1. Also fixes javadoc error 'self-closing element not allowed' for generated doc when building javadoc with JDK 8.
Fixes javadoc error 'self-closing element not allowed' when building javadoc with JDK 8.
Also remove unused imports.
Merge pull request #252 from bhamail/master

Fixes to build javadoc with maven 3.2.1 and jdk8.