added XML Schema reference to site.xml
added XML Schema reference to site.xml

git-svn-id: f1a17a061676d963c74b394b439ef1ab9f189971@10676 52ab4f32-60fc-0310-b215-8acea882cd1b

mohanaraosv/properties-maven-plugin,akuhtz/properties-maven-plugin,mojohaus/properties-maven-plugin,ozimov/yaml-properties-maven-plugin,ozimov/yaml-properties-maven-plugin