The flip6 build profile only runs the Flip-6 related test cases. Moreover,
all Flip-6 related test cases are excluded when not running the flip6 build
profile. This should reduce testing time when adding more and more Flip-6
test cases.

Include flink-test-utils-junit in all submodules to make the Category marker interfaces Flip6 and OldAndFlip6 available

This closes #4889.

Disable it in most modules.

This also makes them optional in flink-runtime, which is enabled by the
previous changes to only use Hadoop dependencies if they are available.

This also requires adding a few explicit dependencies in other modules
because they were using transitive dependencies of the Hadoop deps. The
most common dependency there is, ha!, commons-io.

This closes #4494.

This closes #4453.

This closes #4384.

Currently, every project in Flink has a hard (compile scope) dependency on the jsr305, slf4j, and log4j
artifacts. That way they are pulled into every fat jar, including user fat jars as soon as they refer to
a connector or library.

This commit changes the behavior in two ways:

  1. It removes the concrete logger dependencies from the root pom file. Instead, it adds them to the
     'flink-core' project. That way, all modules that refer to 'flink-core' will have those dependencies
     as well, but the projects that have 'flink-core' as provided (connectors, libraries, user programs,
     etc) will have those dependencies transitively as provided as well.

  2. The commit overrides the slf4j and jsr305 dependencies in the parents of 'flink-connectors',
     'flink-libraries', and 'flink-metrics' and sets the to 'provided'. That way all core projects
     pull the logger classes, but all projects that are not part of flink-dist (and rather bundled
     in fat jars) will not bundle these dependencies again.

The flink-dist puts the dependencies into the fat jar (slf4j, jsr305) or the lib folder (log4j).

This closes #2850

[FLINK-4315] [dataSet] [hadoopCompat] Annotate Hadoop-related methods in ExecutionEnvironment as @Deprecated.

- Preparation to remove Hadoop dependency from flink-java
- Alternatives for deprecated functionality is provided in flink-hadoop-compatibility via HadoopInputs

This closes #2637.

This moves the API compatibility checks into the API projects that use stability annotations.
Previously, every project ran the tests, regardless of whether it contained public API classes or not.

This closes #2334

This closes #2324

Makes the JUnit test utils (TestLogger, retry rules, ...) properly available to
other projects without the 'flink-core' test-jar, via the 'flink-test-utils-junit' project.

Makes the ForkableMiniCluster, TestEnvironment,  and other test utilities available in the 'main'
scope of the 'flink-test-utils' project.

Creates a 'flink-test-utils-parent' project that holds the 'flink-test-utils-junit' and
'flink-test-utils' project.

Also moves some tests between projects and inlines some very simple utility functions in
order to simplify some test jar dependencies.

- replaced CharSets with StandardCharsets
- added checkElementIndex to Flink Preconditions
- replaced Guava Preconditions with Flink Preconditions
- removed single usages Ints.max() and Joiner()

This closes #1938

This closes #1428

The auto-magic for Joda Time was limited to very few classes. It was intransparent what
cases would be handled.

This closes #1535.

This closes #1331

0.10-SNAPSHOT continues on branch release-0.10

[FLINK-2584] [java api] Downgrade version of javakaffee kryo serializers, for compatibility with kryo 2.4

This is needed because the Hadoop IF/OF's are using Hadoop's FileSystem stack, which is using
the security credentials passed in the JobConf / Job class in the getSplits() method.

Note that access to secured Hadoop 1.x using Hadoop IF/OF's is not possible with this change.
This limitation is due to missing methods in the old APIs.

- Add some comments & change dependency scope to test

[FLINK-1901] [core] enable sample with fixed size on the whole dataset.

[FLINK-1901] [core] add more comments for RandomSamplerTest.

[FLINK-1901] [core] refactor PoissonSampler output Iterator.

[FLINK-1901] [core] move sample/sampleWithSize operator to DataSetUtils.

Adds notes for commons-math3 to LICENSE and NOTICE file

This closes #949.

Closes #851