Fix Cygwin support in several scripts.

This allows the spark-shell, spark-class, run-example, make-distribution.sh,
and ./bin/start-* scripts to work under Cygwin.  Note that this doesn't
support PySpark under Cygwin, since that requires many additional `cygpath`
calls from within Python and will be non-trivial to implement.

This PR was inspired by, and subsumes, #253 (so close #253 after this is merged).
Fixed a performance problem in RDD.top and BoundedPriorityQueue (size in BoundedPriority was actually traversing the entire queue to calculate the size, resulting in bad performance in insertion).
Fixed the example link.
Merge pull request #273 from rxin/top

Fixed a performance problem in RDD.top and BoundedPriorityQueue

BoundedPriority was actually traversing the entire queue to calculate the size, resulting in bad performance in insertion.

This should also cherry pick cleanly into branch-0.8.
changed the example links in the scala-programming-guid
Merge pull request #274 from azuryy/master

Fixed the example link in the Scala programing guid.

The old link cannot access, I changed to the new one.
Merge pull request #267 from JoshRosen/cygwin

Fix Cygwin support in several scripts.

This allows the spark-shell, spark-class, run-example, make-distribution.sh,
and ./bin/start-* scripts to work under Cygwin.  Note that this doesn't
support PySpark under Cygwin, since that requires many additional `cygpath`
calls from within Python and will be non-trivial to implement.

This PR was inspired by, and subsumes, #253 (so close #253 after this is merged).
In experimental clusters we've observed that a 10 second timeout was insufficient,
despite having a low number of nodes and relatively small workload (16 nodes, <1.5 TB data).
This would cause an entire job to fail at the beginning of the reduce phase.
There is no particular reason for this value to be small as a timeout should only occur
in an exceptional situation.

Also centralized the reading of spark.akka.askTimeout to AkkaUtils (surely this can later
be cleaned up to use Typesafe).

Finally, deleted some lurking implicits. If anyone can think of a reason they should still
be there, please let me know.
Merge pull request #247 from aarondav/minor

Increase spark.akka.askTimeout default to 30 seconds

In experimental clusters we've observed that a 10 second timeout was insufficient, despite having a low number of nodes and relatively small workload (16 nodes, <1.5 TB data). This would cause an entire job to fail at the beginning of the reduce phase.
There is no particular reason for this value to be small as a timeout should only occur in an exceptional situation.

Also centralized the reading of spark.akka.askTimeout to AkkaUtils (surely this can later be cleaned up to use Typesafe).

Finally, deleted some lurking implicits. If anyone can think of a reason they should still be there, please let me know.
[SPARK-959] Explicitly depend on org.eclipse.jetty.orbit jar

Without this, in some cases, Ivy attempts to download the wrong file
and fails, stopping the whole build. See bug for more details.

(This is probably also the beginning of the slow death of our
recently prettified dependencies. Form follow function.)
Merge pull request #183 from aarondav/spark-959

[SPARK-959] Explicitly depend on org.eclipse.jetty.orbit jar

Without this, in some cases, Ivy attempts to download the wrong file and fails, stopping the whole build. See [bug](https://spark-project.atlassian.net/browse/SPARK-959) for more details.

Note that this may not be the best solution, as I do not understand the root cause of why this only happens for some people. However, it is reported to work.