svn merge 1445964:1445965 from trunk to branch-2 to fix HDFS-4495.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1445968 13f79535-47bb-0310-9956-ffa450edef68
HADOOP-8924. Add maven plugin alternative to shell script to save package-info.java. Contributed by Alejandro Abdelnur and Chris Nauroth.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1446018 13f79535-47bb-0310-9956-ffa450edef68
HADOOP-9245. mvn clean without running mvn install before fails. Contributed by Karthik Kambatla.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1446019 13f79535-47bb-0310-9956-ffa450edef68
HADOOP-9246. Execution phase for hadoop-maven-plugin should be process-resources. Contributed by Karthik Kambatla and Chris Nauroth

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1446020 13f79535-47bb-0310-9956-ffa450edef68
HADOOP-9117. replace protoc ant plugin exec with a maven plugin. (tucu)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1446021 13f79535-47bb-0310-9956-ffa450edef68
HADOOP-9246. Amending CHANGES.txt

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1446023 13f79535-47bb-0310-9956-ffa450edef68