HAMA-829: Improve code and fix Javadoc warnings in org.apache.hama.pipes

git-svn-id: https://svn.apache.org/repos/asf/hama/trunk@1550674 13f79535-47bb-0310-9956-ffa450edef68
Minor refactor

git-svn-id: https://svn.apache.org/repos/asf/hama/trunk@1551092 13f79535-47bb-0310-9956-ffa450edef68
Merge branch 'trunk' of git://git.apache.org/hama into trunk

Conflicts:
	c++/src/main/native/pipes/api/hama/Pipes.hh