Simplify os::hostname() in libstout.
Hadoop changes; see below.

    - Added CDH4.2.0 support to TUTORIAL.sh
    - Fixed Hadoop dist extraction in launcher
    - Add pre/post packaging hooks to TUTORIAL.sh
    - Don't run the jobtracker at the end by default if ${SKIP_TESTS}
      defined
Fixed a deadlock in the Hadoop MesosScheduler by unsynchronizing
resourceOffers().

https://reviews.apache.org/r/10352/diff/2/