Adding a general handler for upgrading protocols

Adding full implementation for cleartext upgrade from HTTP to HTTP/2.
Add unified NextProtoNego extension support to SslContext

Motivation:

- OpenSslEngine and JDK SSLEngine (+ Jetty NPN) have different APIs to
  support NextProtoNego extension.
  - It is impossible to configure NPN with SslContext when the provider
    type is JDK.

Modification:

- Implement NextProtoNego extension by overriding the behavior of
  SSLSession.getProtocol() for both OpenSSLEngine and JDK SSLEngine.
  - SSLEngine.getProtocol() returns a string delimited by a colon (':')
    where the first component is the transport protosol (e.g. TLSv1.2)
    and the second component is the name of the application protocol
- Remove the direct reference of Jetty NPN classes from the examples
- Add SslContext.newApplicationProtocolSelector

Result:

- A user can now use both JDK SSLEngine and OpenSslEngine for NPN-based
  protocols such as HTTP2 and SPDY
Update the instruction for running SPDY examples
Escape a colon in protocol names
Fix NPE in OpenSslEngine
Merge branch 'master' of https://github.com/netty/netty into http2

Conflicts:
	example/src/main/java/io/netty/example/http2/client/Http2Client.java
	example/src/main/java/io/netty/example/http2/client/Http2ClientInitializer.java
	example/src/main/java/io/netty/example/http2/server/Http2Server.java
	example/src/main/java/io/netty/example/http2/server/Http2ServerInitializer.java
Merge pull request #2496 from nmittler/http2

Adding a general handler for upgrading protocols
Future compatibility with TLS ALPN

Motivation:

According to TLS ALPN draft-05, a client sends the list of the supported
protocols and a server responds with the selected protocol, which is
different from NPN.  Therefore, ApplicationProtocolSelector won't work
with ALPN

Modifications:

- Use Iterable<String> to list the supported protocols on the client
  side, rather than using ApplicationProtocolSelector
- Remove ApplicationProtocolSelector

Result:

Future compatibility with TLS ALPN
Checkstyle
Fix NPE
Fix an event ordering issue

Motivation:

In the early days of 5.0, we merged ChannelInboundHandler and
ChannelOutboundHandler into ChannelHandler, and introduced the
annotation called 'Skip'.  The annotation 'Skip' was introduced to
determine which handler methods are no-op (i.e. simply forwarding the
event to the next handler) so that DefaultChannelHandlerContext doesn't
even need to submit an event-invoking task to an EventExecutor,
significantly reducing the context switches.

However, this introduced a regression for the handlers which implemented
write() but not flush(). Because flush() was skippable for such
handlers, flush() event went through to the next handler before write() does.

To address this problem, we came up with a naive workaround that sets
MASK_FLUSH when MASK_WRITE is set.

Although the previous workaround works fine for many cases, we still
seem to have an event ordering problem.  We keep seeing the intermittant
failure of LocalTransportThreadModelTest.testStagedExecution(), because
other handler methods are still skipped.

Modifications:

We do not skip the execution of handler methods annotated with 'Skip'
unless all inbound methods (or all outbound methods) are marked with
'Skip'.

Result:

This change Brings back the event ordering behavior of 4.x, making
LocalTransportThreadModelTest.testStagedExecution() pass.
Display example names in 2 columns

- ported from ba286797752851e4d4426661fffda2f12feb7920
Fix an incorrect path problem in run-example.sh
Use maven-antrun-plugin instead of exec-maven-plugin

Motivation:

exec-maven-plugin does not flush stdout and stderr, making the console
output from the examples invisible to users

Modification:

Use maven-antrun-plugin instead

Result:

A user sees the output from the examples immediately.
Fix packagine issues in all-in-one JAR

Motivation:

- dependencyVersionsDir property is not resolved during the build
  process. The build doesn't fail because of this, but it creates an
  ugly directory.
- All-in-one JAR contains libnetty-tcnative.so, which is not part of the
  all-in-one JAR.

Modifications:

- Fix an incorrect property name
  (dependencyVersionDir -> dependencyVersionsDir)
- Exclude libnetty-tcnative.so
- Remove unnecessary includes in source expanding configuration

Result:

- Cleaner pom.xml
- We do not ship libnetty-tcnative.so in all-in-one JAR anymore, which
  is correct, because strictly speaking the native library belongs to
  org.apache.tomcat.jni package.
Fix a regression introduced by 00853d94537c8bb648107f2cb8889d1c65e99886

.. by fixing incorrect bitwise operation for pipeline traversal
Fix a bug in DefaultPromise.notifyLateListener() where the listener is not notified

Motivation:

When (listeners == null && lateListeners == null) and (stackDepth >= MAX_LISTENER_STACK_DEPTH), the listener is not notified at all. The discard client does not work.

Modification:

Make sure to submit the notification task.

Result:

The discard client works again and all listeners are notified.
Clean up the examples

Motivation:

The examples have not been updated since long time ago, showing various
issues fixed in this commit.

Modifications:

- Overall simplification to reduce LoC
  - Use system properties to get options instead of parsing args.
  - Minimize option validation
  - Just use System.out/err instead of Logger
  - Do not pass config as parameters - just access it directly
  - Move the main logic to main(String[]) instead of creating a new
    instance meaninglessly
    - Update netty-build-21 to make checkstyle not complain
  - Remove 'throws Exception' clause if possible
- Line wrap at 120 (previously at 80)
- Add an option to enable SSL for most examples
- Use ChannelFuture.sync() instead of await()
- Use System.out for the actual result. Use System.err otherwise.
- Delete examples that are not very useful:
  - applet
  - websocket/html5
  - websocketx/sslserver
  - localecho/multithreaded
- Add run-example.sh which simplifies launching an example from command
  line
- Rewrite FileServer example

Result:

Shorter and simpler examples.  A user can focus more on what it actually
does than miscellaneous stuff.  A user can launch an example very
easily.
Use a forked exec-maven-plugin instead of maven-antrun-plugin

Motivation:

maven-antrun-plugin does not redirect stdin, and thus it's impossible to
run interactive examples such as securechat-client and telnet-client.
org.codehaus.mojo:exec-maven-plugin redirects stdin, but it buffers
stdout and stderr, and thus an application output is not flushed timely.

Modifications:

Deploy a forked version of exec-maven-plugin which flushes output
buffers in a timely manner.

Result:

Interactive examples work.  Launches faster than maven-antrun-plugin.
Upgrade os-maven-plugin to fix an issue with IntelliJ IDEA on Windows