This closes #258

- This commit introduces reference-counting to keep track of the
  InputChannel and OutputChannel instances, which share the same
  physical TCP connection.

- When the logical channels are released, the reference count will
  reach 0 and the respective TCP connection can safely be closed.

- Furthermore, the debug thread in the OutboundConnectionQueue is
  properly shut down and all queued buffers are freed when the
  channel is closed or an Exception occurs.

This closes #255.

This commit is based on a diff by @fpompermaier (see https://github.com/apache/incubator-flink/pull/220).

This closes #220

This closes #262.

This closes #261.

java complains about not expecting an interface here. Needs to be `implements` instead of `extends`.

This closes #257

This closes #194

Renamed org.apache.flink.example package to org.apache.flink.examples
Default data is provided from flink-java examples

[streaming] Documentation added for streaming java 8 support

This closes #173

[FLINK-1139] Added FinalizeOnMaster hook to run code after the last task of an OutputFormat completed

Made exceptions for license check plugin more fine-granular.

This closes #250

Before, it was not doing a proper deep copy of the fields.

[streaming] Changed GroupedWindowInvokable to always delete groups in case they have an empty element buffer

[streaming] Updated streaming-guide to match recent api changes

[streaming] Extended test cases for grouped window invokable to cover usage of central eviction policies

[streaming] Renamed test cases for window and grouped window invokable to be consistent with the invokable names

[streaming] Changed time based windowing policies to make lower boundary excluded and upper boundary included in the windows and adjusted policy test cases respectively.