Migrating to Protobuf 2.5.0

Unable to run Spark 0.9.0 on Apache Mesos with Hadoop HDFS 2.*. There is
a discrepancy in the Protobuffer version used. Mesos 0.16.0 uses 2.4.1
and Hadoop HDFS 2.* uses 2.5.0.

[ticket: X] : ?
Merge pull request #1 from berngp/0.16.0/hotfix/HDP_2.2

Migrating to Protobuf 2.5.0