Before, when one source closes early it will not emit watermarks
anymore. Downstream operations don't know about this and expect
watermarks to keep on coming. This leads to watermarks not being
forwarded anymore.

Now, when a source closes it will emit a final watermark with timestamp
Long.MAX_VALUE. This will have the effect of allowing the watermarks
from the other operations to propagate though because the watermark is
defined as the minimum over all inputs.

The Long.MAX_VALUE watermark has the added benefit of notifying
operations that no more elements will arrive in the future.

This closes #1060

This closes #1114

This closes #941

This closes #1111

[FLINK-2645] [jobmanager] Fail job execution if final accumulators cannot be merged and forward exceptions.

This closes #1112

[FLINK-2631] [streaming] Fixes the StreamFold operator and adds OutputTypeConfigurable interface to support type injection at StreamGraph creation.

Adds test for non serializable fold type. Adds test to verify proper output type forwarding for OutputTypeConfigurable implementations.
Makes OutputTypeConfigurable typed, tests that TwoInputStreamOperator is output type configurable

This closes #1101

This closes #1100

This closes #1109

This closes #1103

..capable of tracking min, max and estimates for count distinct and
heavy hitters.

The count distinct algorithms are Linear Counting and HyperLogLog, both
from an imported library from clearspring.

The heavy hitters algorithms are Lossy counting (Manku et.al 2002) and
one based on Count Min Sketch (Cormode 2005).

The heavy hitters algorithms are implemented in the statistics package
in the flink-operator-stats submodule of flink-contrib.

Include tests verifying if merged skecthes have the same guarantees as
local sketches.

Added conditional to every collect variable, to make stats more
configurable. Made print operator stats more informative. Added
arguments to yarn pom to enable building

Implemented deep cloning for class OperatorStatistics. Added additional
tests in OperatorStatsAccumulatorTest to check if the accumulator works
when only one statistic is being tracked, rather than all.

This closes #605.

This closes #1094

This closes #1091

This also bumps surefire/failsafe version to 2.8.1

This closes #889.

[FLINK-2580] [runtime] Expose more methods form Hadoop output streams and exposes wrapped input and output streams.

This closes #1093

This closes #992.

This closes #1052

- improve test layout

This closes #1073.

[FLINK-2570] [gelly] Added a description of the I/O

This closes #1054

[FLINK-2567] [core] Allow quoted strings in CSV fields to contain quotation character inside of the field, as long as its escaped Ex: 'Hi my name is \'Flink\''

This closes #1059

This closes #1082

This closes #1096

The test is inconclusive when the test failure happens before the first checkpoint.

LocalExecutor and Client now pass Configuration to JobGraphGenerator.

This closes #1095

This closes #1089.

[FLINK-2161] [scala shell] Modify start script to take additional argument (-a <path/to/class> or --addclasspath <path/to/class>) for external libraries

This closes #805

This closes #1074

- call new start() method of FlinkMiniCluster

This closes #1085.