This closes #2042

This closes #1981

- Fix FLINK-3696 (type issues of DataSetUnion by forwarding expected types to input operators).

This closes #2025

This closes #2035

This closes #1956

- Add unit tests for Aggretates.

This closes #2024

We should use java.util.concurrent.ConcurrentHashMap because Netty's
ConcurrentHashMap is not available for Hadoop 1. Also, Netty's ConcurrentHashMap
is merely a copy of Java's to support Java versions prior 1.5.

This closes #2026

Until FLINK-3960 is fixed, we need to disable this test to allow other
tests to execute properly.

This closes #2022

This closes #2018

This closes #2023

This closes #2015

This closes #2014

After 38698c0b, there are now two
executions defined for the Surefire plugin: unit-tests and
integration-tests. In addition, there is an implicit default execution
called default-test. This leads to the unit tests to be executed
twice. This renames unit-tests to default-test to prevent duplicate
execution.

This closes #2019

- introduce a unique container id independent of the Hadoop version
- improve printing of exceptions during registration
- minor improvements to the Yarn ResourceManager code

This closes #2013

  - Metric groups are generally thread-safe
  - Metric groups are closable. Closed groups do not register metric objects and more.
  - TaskManager's JobMetricsGroup auto disposes when all TaskMetricGroups are closed
  - Maven project with metric reporters renamed to 'flink-metric-reporters'
  - Various code style cleanups

The Jaccard Index measures the similarity between vertex neighborhoods.
Scores range from 0.0 (no shared neighbors) to 1.0 (all neighbors are
shared).

This closes #1980

This closes #2006

As of 70978f56, the Yarn tests were not
executed anymore. They were moved to the test directory but there was
still a Maven configuration in place to change the test directory
location.

This closes #2012

Failures during execution of the integration tests with the Maven
Failsafe plugin were silently ignored on Travis with Maven version
3.2.5. The problem is that failures are not passed on correctly from the
'integration-test' phase (where failures are recorded and tolerated) to
the 'verify' phase.

The cause of the error is most likely SUREFIRE-1127. An exception in the
'integration-test' is sometimes not flushed back to disk where it is
evaluated in the 'verify' phase. Bumping the version of the Failsafe
plugin from 2.18.1 to 2.19.1 fixes the issue but introduces classpath
related problems.

We don't have to rely on Failsafe for running integration
tests. Surefire offers the same feature set we use from the Failsafe
plugin.

- replace Failsafe with Surefire
- update to latest Surefire version
- get rid of duplicate property declaration

This closes #2003

- increase timeout for task managers to be registered
- don't fail if leader retrieval service has not been started yet

This closes #2009

This fixes a NullPointerException that would occur if the host name
could not be resolved.

This closes #2008

[FLINK-3933] [streaming API] Add AbstractDeserializationSchema that handles produced type extraction.

The AbstractDeserializationSchema creates the produced type information automatically from the
generic parameters.

This closes #2010

Very simple fix for typo on comment in the task manager.sh file.

From `JobManager` to `TaskManager`.

Author: Henry Saputra <hsaputra@apache.org>

Closes #2001 from hsaputra/simple_text_fix_taskmanager and squashes the following commits:

861cbb4 [Henry Saputra] Simple fix of typo from JobManager to TaskManager in taskmanager.sh file.

- New Input- and OutputFormat use Row instead of Tuple types to support null values.
- JdbcInputFormat supports parallel input due to PreparedStatement and binding values for parameters.

This closes #1941

This closes #2000