We can do this now that we dropped support for Scala 2.10.

This closes #4807

Creates a separate for the queryable state and  moves the client
code outside the runtime. The Task Manager is now instantiating
the KvStateServer using reflection.

  - Set shorter heartbeats intervals. Default pause value of 60seconds is
    too large (tests would timeout before akka react)

  - Exclude netty dependency from zookeeper. Zookeeper was pulling in
    conflicting Netty version. Conflict was extremly subtle - TaskManager in
    Kafka tests was deadlocking in some rare corner cases.

This closes #4775

This changes the discovery mechanism of file from static class name configurations
to a service mechanism (META-INF/services).

As part of that, it factors HDFS and MapR FS implementations into separate modules.

With this change, users can add new filesystem implementations and make them available
by simply adding them to the class path.

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 also adds an end-to-end test that verifies correct order for both
classes and resources.

This closes #4503.

This closes #4494.

This closes #4452.

This closes #4367.

This closes #4461.

Because we're now using Java 8 we have to disable linting also when not
using the (now-removed) jdk8 profile or the release profile.

Because of this problem snapshot deployments were not working.

This closes #4399.

This closes #4398.

This closes #4319.

This closes #4160.

This closes #4205

Default values for compiler version are 1.6 and were causing Intellij to
constantly switch language level to 1.6, which in turn was causing
compilation errors. It worked fine for compiling from console using
maven, because those values are separetly set in maven-compiler-plugin
configuration.

This closes #4213.

This closes #4209.

This closes #3833.

- enable sudo for more memory
- increase java heap size
- replace usage of oraclejdk7 since it is no longer supporter
- manually install maven 3.2.5

This closes #4182.

This closes #4017.

[FLINK-6836] [tests] Fix YARNSessionCapacitySchedulerITCase to work with Hadoop 2.6.5, 2.7.3 and 2.8.0

Due to MNG-5899, maven cannot resolve dependency reduced poms in a multi project build. Therefore,
flink-yarn-tests pulls in a wrong version of org.apache.httpcomponents.httpclient which does not work
with Hadoop's ServletUtils together. As a solution we have to move the dependency management for the
httpclient and httpcore version into the parent pom.xml.

Another problem is the version of these libraries which has been recently bumped. In 4.4, httpclient
changed its behaviour such that URLEncodedUtils#parse(String, Charset) now throws a NPE if the first
parameter is null. In 4.2.6, an empty list was returned instead. Due to this incompatibility, we reverted
the change and set the version to its previous value.

Bump httpclient to 4.5.3 and httpcore to 4.4.6

This closes #4120.

This closes #4048

Update Hadoop versions and replace Hadoop 2.3 with 2.8 in build and
continuous integration scripts. flink-yarn-tests can now be enabled for
all supported Hadoop versions and is made non-optional.

This closes #3832

Upgrade to the last maintenance releases of Scala 2.10 and 2.11.

This closes #3957

Configure a default value for Maven variable 'flink.forkCountTestPackage'.

This closes #3875

This closes #3854.

This closes #3495.