SPARK-1996. Remove use of special Maven repo for Akka

Just following up Matei's suggestion to remove the Akka repo references. Builds and the audit-release script appear OK.

Author: Sean Owen <sowen@cloudera.com>

Closes #1170 from srowen/SPARK-1996 and squashes the following commits:

5ca2930 [Sean Owen] Remove outdated Akka repository references
SPARK-2231: dev/run-tests should include YARN and use a recent Hadoop version

...rsion

Author: Patrick Wendell <pwendell@gmail.com>

Closes #1175 from pwendell/test-hadoop-version and squashes the following commits:

9210ef4 [Patrick Wendell] SPARK-2231: dev/run-tests should include YARN and use a recent Hadoop version
SPARK-2034. KafkaInputDStream doesn't close resources and may prevent JVM shutdown

Tobias noted today on the mailing list:

========

I am trying to use Spark Streaming with Kafka, which works like a
charm – except for shutdown. When I run my program with "sbt
run-main", sbt will never exit, because there are two non-daemon
threads left that don't die.
I created a minimal example at
<https://gist.github.com/tgpfeiffer/b1e765064e983449c6b6#file-kafkadoesntshutdown-scala>.
It starts a StreamingContext and does nothing more than connecting to
a Kafka server and printing what it receives. Using the `future
Unknown macro: { ... }
` construct, I shut down the StreamingContext after some seconds and
then print the difference between the threads at start time and at end
time. The output can be found at
<https://gist.github.com/tgpfeiffer/b1e765064e983449c6b6#file-output1>.
There are a number of threads remaining that will prevent sbt from
exiting.
When I replace `KafkaUtils.createStream(...)` with a call that does
exactly the same, except that it calls `consumerConnector.shutdown()`
in `KafkaReceiver.onStop()` (which it should, IMO), the output is as
shown at <https://gist.github.com/tgpfeiffer/b1e765064e983449c6b6#file-output2>.
Does anyone have any idea what is going on here and why the program
doesn't shut down properly? The behavior is the same with both kafka
0.8.0 and 0.8.1.1, by the way.

========

Something similar was noted last year:

http://mail-archives.apache.org/mod_mbox/spark-dev/201309.mbox/%3C1380220041.2428.YahooMailNeo@web160804.mail.bf1.yahoo.com%3E

KafkaInputDStream doesn't close `ConsumerConnector` in `onStop()`, and does not close the `Executor` it creates. The latter leaves non-daemon threads and can prevent the JVM from shutting down even if streaming is closed properly.

Author: Sean Owen <sowen@cloudera.com>

Closes #980 from srowen/SPARK-2034 and squashes the following commits:

9f31a8d [Sean Owen] Restore ClassTag to private class because MIMA flags it; is the shadowing intended?
2d579a8 [Sean Owen] Close ConsumerConnector in onStop; shutdown() the local Executor that is created so that its threads stop when done; close the Zookeeper client even on exception; fix a few typos; log exceptions that otherwise vanish