Simplified os::hostname() in libstout.

Review: https://reviews.apache.org/r/11108
Included pre/post-package hooks in Hadoop tutorial.

Review: https://reviews.apache.org/r/11110
Allowed ending Hadoop tutorial early.

You may also skip the test part by exporting SKIP_TESTS (i.e., 'make
hadoop SKIP_TESTS=1').

Review: https://reviews.apache.org/r/11111
Added check for Python.h in configure script.

Review: https://reviews.apache.org/r/11114
Switched to more portable paths for tutorial test.

Review: https://reviews.apache.org/r/11115
Be more intelligent about slot allocation.

When we get a resource offer, we'll try to be clever about how we
allocate slots to the offers.  Ideally we want to use as much of the
resources available when we have a lot of pending tasks, and we also
don't want to use more resources than we actually need.

Review: https://reviews.apache.org/r/13078
Don't prematurely kill TaskTrackers.

We assign the JobID to the internal Mesos tracker (for the TaskTracker)
rather than the TaskID.

In the case where a TaskTracker has only map tasks assigned to it and
they have all completed, we mustn't terminate the tracker until the
entire job has finished, including the map tasks.

Review: https://reviews.apache.org/r/11119
Shuffle offers before sending to frameworks.

This helps ensure fair allocation of resources.

Review: https://reviews.apache.org/r/11121
Kill tasks that never properly launch.

After trying to launch a task tracker, we'll wait up to 5 minutes before
giving up and killing the task.

Review: https://reviews.apache.org/r/11124
Allowed some JVM memory vars to be configured.

Also modified the slot CPU/mem values to be more sane defaults.

Review: https://reviews.apache.org/r/11130
No longer accept offers on the same host/port.

We'll try to find a port combination that hasn't already been used to
launch a TaskTracker.

Review: https://reviews.apache.org/r/11161/
Write Mesos JobTracker stats to state file.

Review: https://reviews.apache.org/r/11165/
s/hadoopJobs/jobs/g in Hadoop scheduler.

Review: https://reviews.apache.org/r/11489
Refactored Hadoop job completion.

Review: https://reviews.apache.org/r/11603
Stop tracker timer when we terminate tasks.

Review: https://reviews.apache.org/r/11604
Added --enable-debug configure flag.

Review: https://reviews.apache.org/r/11605
Slave ping timeout may be increased by flags.

Review: https://reviews.apache.org/r/12885
Use XZ (LZMA) for package on Linuxes.

Review: https://reviews.apache.org/r/11112
Turned down noise from ZooKeeper.

Review: https://reviews.apache.org/r/11127
Fixed hadoop 0.20.205.0 dist.

Review: https://reviews.apache.org/r/11662