SPARK-1818 Freshen Mesos documentation

Place more emphasis on using precompiled binary versions of Spark and Mesos
instead of encouraging the reader to compile from source.

Author: Andrew Ash <andrew@andrewash.com>

Closes #756 from ash211/spark-1818 and squashes the following commits:

7ef3b33 [Andrew Ash] Brief explanation of the interactions between Spark and Mesos
e7dea8e [Andrew Ash] Add troubleshooting and debugging section
956362d [Andrew Ash] Don't need to pass spark.executor.uri into the spark shell
de3353b [Andrew Ash] Wrap to 100char
7ebf6ef [Andrew Ash] Polish on the section on Mesos Master URLs
3dcc2c1 [Andrew Ash] Use --tgz parameter of make-distribution
41b68ed [Andrew Ash] Period at end of sentence; formatting on :5050
8bf2c53 [Andrew Ash] Update site.MESOS_VERSIOn to match /pom.xml
74f2040 [Andrew Ash] SPARK-1818 Freshen Mesos documentation
SPARK-1828: Created forked version of hive-exec that doesn't bundle other dependencies

See https://issues.apache.org/jira/browse/SPARK-1828 for more information.

This is being submitted to Jenkin's for testing. The dependency won't fully
propagate in Maven central for a few more hours.

Author: Patrick Wendell <pwendell@gmail.com>

Closes #767 from pwendell/hive-shaded and squashes the following commits:

ea10ac5 [Patrick Wendell] SPARK-1828: Created forked version of hive-exec that doesn't bundle other dependencies
[SPARK-1620] Handle uncaught exceptions in function run by Akka scheduler

If the intended behavior was that uncaught exceptions thrown in functions being run by the Akka scheduler would end up being handled by the default uncaught exception handler set in Executor, and if that behavior is, in fact, correct, then this is a way to accomplish that.  I'm not certain, though, that we shouldn't be doing something different to handle uncaught exceptions from some of these scheduled functions.

In any event, this PR covers all of the cases I comment on in [SPARK-1620](https://issues.apache.org/jira/browse/SPARK-1620).

Author: Mark Hamstra <markhamstra@gmail.com>

Closes #622 from markhamstra/SPARK-1620 and squashes the following commits:

071d193 [Mark Hamstra] refactored post-SPARK-1772
1a6a35e [Mark Hamstra] another style fix
d30eb94 [Mark Hamstra] scalastyle
3573ecd [Mark Hamstra] Use wrapped try/catch in Utils.tryOrExit
8fc0439 [Mark Hamstra] Make functions run by the Akka scheduler use Executor's UncaughtExceptionHandler