Update javadoc.

git-svn-id: https://svn.apache.org/repos/asf/logging/log4j/log4j2/trunk@1615473 13f79535-47bb-0310-9956-ffa450edef68
Add link to commons-lang to dissuade users from using internal class.

git-svn-id: https://svn.apache.org/repos/asf/logging/log4j/log4j2/trunk@1615474 13f79535-47bb-0310-9956-ffa450edef68
Add javadoc for remaining methods.

git-svn-id: https://svn.apache.org/repos/asf/logging/log4j/log4j2/trunk@1615475 13f79535-47bb-0310-9956-ffa450edef68
Elaborate the LogManager intro javadoc.

git-svn-id: https://svn.apache.org/repos/asf/logging/log4j/log4j2/trunk@1615476 13f79535-47bb-0310-9956-ffa450edef68
Fix HTML in javadoc.

git-svn-id: https://svn.apache.org/repos/asf/logging/log4j/log4j2/trunk@1615477 13f79535-47bb-0310-9956-ffa450edef68