SPARK-1136: Fix FaultToleranceTest for Docker 0.8.1

This patch allows the FaultToleranceTest to work in newer versions of Docker.
See https://spark-project.atlassian.net/browse/SPARK-1136 for more details.

Besides changing the Docker and FaultToleranceTest internals, this patch also changes the behavior of Master to accept new Workers which share an address with a Worker that we are currently trying to recover. This can only happen when the Worker itself was restarted and got the same IP address/port at the same time as a Master recovery occurs.

Finally, this adds a good bit of ASCII art to the test to make failures, successes, and actions more apparent. This is very much needed.

Author: Aaron Davidson <aaron@databricks.com>

Closes #5 from aarondav/zookeeper and squashes the following commits:

5d7a72a [Aaron Davidson] SPARK-1136: Fix FaultToleranceTest for Docker 0.8.1
SPARK-1195: set map_input_file environment variable in PipedRDD

Hadoop uses the config mapreduce.map.input.file to indicate the input filename to the map when the input split is of type FileSplit. Some of the hadoop input and output formats set or use this config. This config can also be used by user code.
PipedRDD runs an external process and the configs aren't available to that process. Hadoop Streaming does something very similar and the way they make configs available is exporting them into the environment replacing '.' with '_'. Spark should also export this variable when launching the pipe command so the user code has access to that config.
Note that the config mapreduce.map.input.file is the new one, the old one which is deprecated but not yet removed is map.input.file. So we should handle both.

Perhaps it would be better to abstract this out somehow so it goes into the HadoopParition code?

Author: Thomas Graves <tgraves@apache.org>

Closes #94 from tgravescs/map_input_file and squashes the following commits:

cc97a6a [Thomas Graves] Update test to check for existence of command, add a getPipeEnvVars function to HadoopRDD
e3401dc [Thomas Graves] Merge remote-tracking branch 'upstream/master' into map_input_file
2ba805e [Thomas Graves] set map_input_file environment variable in PipedRDD