Publish Maven javadoc and sources artifacts with Hadoop releases.

Right now Maven javadoc and sources artifacts do not accompany Hadoop releases within Maven central. This means that one needs to checkout source code to DEBUG aspects of the codebase... this is not user friendly.

The build script(s) should be amended to accommodate publication of javadoc and sources artifacts alongside pom and jar artifacts.

Some history on this conversation can be seen below
http://s.apache.org/7qR