Fix #2275 %s WebSocket version %s server handshake
Add ZLIB_OR_NONE support to JdkZlibDecoder [#2016]
Added asserts to make sure ChannelHandlers are removed from the pipeline
Correct ConcurrentHashMapV8 bitwise arithmetic

Previously ConcurrentHashMapV8 evaulated ((x | 1) == 0), an expression
that always returned false.  This commit brings Netty closer to the
Java 8 implementation.
Added a secure WebSocket client example

Merged WebSocketClient and WebSocketSslClient

Add private constructors to fix checkstyle errors.

More checkstyle madness.

made WebSocketClientRunner final
[#2261] Correct javadoc of ChunkedInput
[#2252] Fix bug where AppendableCharSequence private constructor does not set correct position
Corrected inconsistencies in the Javadoc.

Port of 80030493b9f7824c02dc88260c2579afc0aed8bc
Ensure the HttpResponseEncoder is always placed before the HttpObjectAggregator. Part of [#2219]
Add CONTRIBUTING.md

Motivation:
We often receive a bug report or a pull request which do not give us
enough information.  If CONTRIBUTING.md exists in the repository, Github
will display some notice in the beginning of the issue submission form,
which might increase the overall quality of the bug reports and pull
requests.

Modification:
Write CONTRIBUTING.md

Result:
Potentially higher-quality bug reports and pull requests
Update CONTRIBUTING.md
Fix buffer leak in test which was introduced while implement ZLIB_OR_NONE support. Related to [#2269]
Add content length and date headers to CORS response
[#2280] Correct logic in Native.finishConnect. Fix use of optval parameter in c getOption function. In epoll event loop, check that channel is open before processing event.
Fix buffer leak in test which was introduced while implement ZLIB_OR_NONE support. Related to [#2269]
added support for empty query parameters
[#2297] Correctly close all registered Channels on EpollEventLoop.closeAll()
ipfilter implementation for netty 4/5 [#2129]
Use bitwise operations to choose next EventExecutor if number of EventExecutors is power of two
Move the pull request guide to the developer guide

Motivation:

CONTRIBUTING.md is useful only because it lets Github show a user the
link to it so the user can check what information we need before
submitting a bug report.  However, Github does not do the same for a
pull request submission form, and thus there's no reason to keep the
information about how to submit a good pull request in CONTRIBUTING.md.

Modification:

Replace the section about issuing a pull request with the link to the
official developer guide.

Result:

CONTRIBUTING.md is easier to maintain.