Add another safe-to-ignore socket error message for SslHandler

.. which covers the 'Software caused connection abort: recv failed' from Windows
Add IPv4 and IPv6 specific localhost constants to NetUtil
Fix 'unsupported address type error' in UDP tests / Fix checkstyle
Unignore DatagramMulticastTest because it seems to pass on Linux, MacOS X, and Windows

More specifically: Ubuntu Linux 13.04, MacOS X Lion, Windows 7
Add more safe-to-ignore exception messages for SslHandler

- Just in case SslHandler is used on UDT
Fix an infinite exception storm triggered by DefaultChannelHandlerContext.invokeInboundBufferUpdated()

- it has to break from the infinite loop when an exception is raised by handler
ChannelHandler.handlerRemoved() must be invoked *after* the handler has been removed completely and its buffers should be inaccessible.
Add a failing test that will pass once #1306 is fixed
Rename methods to catch up the recent changes in handler life cycle listener methods / Ensure to call handlerRemoved() even if ctx.forwardContentAndRemove() failed
Format
Move multiplicity check to the early stage

.. no need to do it late
Make sure handlerAdded() is called before forwarding the buffer content of the removed handler

- Added a test case that reproduces the problem in ReplayingDecoderTest
- Call newHandler.handlerAdded() *before* oldHandler.handlerRemoved() to ensure newHandlerAdded() is called before forwarding the buffer content of the old handler in replace0().
Remove freeInboundBuffer() and freeOutboundBuffer() which has no value

- Fixes #1308

freeInboundBuffer() and freeOutboundBuffer() were introduced in the early days of the new API when we did not have reference counting mechanism in the buffer. A user did not want Netty to free the handler buffers had to override these methods.

However, now that we have reference counting mechanism built into the buffer, a user who wants to retain the buffers beyond handler's life cycle can simply return the buffer whose reference count is greater than 1 in newInbound/OutboundBuffer().
[#1309] Make sure ReplayDecoder respect isSingleDecode()

* This could cause for example corrupt WebSocketFrame's if they was written from the server
  to the client directly after it send the handshake response.
Fix test failure in testsuite-osgi-deps

This commit fixes both failure of test itself and failure of compiling
and running test.

- When the test was run via 'mvn test', Maven gives karaf-maven-plugin a
  list of class directories instead of OSGi bundles, so that
  karaf-maven-plugin generates incorrect feature.xml.  I added a
  workaround for this specific case to DependencyIT
- When the packaging of project is 'feature', maven-compiler-plugin is
  not run at all.  Added a <plugin/> section so that it's always
  compiled.
Rename Unsafe.directOutboundContext to headContext
Allow to disable only heap or direct buffer pool

- Fixes #1315

If a user specifies the arena size of 0, the pool is now disabled
instead of raising an IllegalArgumentException. Using this, you can
disable only heap or direct buffer pool easily. Once disabled,
PooledByteBufAllocator will delegate the allocation request to
UnpooledByteBufAllocator.
Fix a bug where HttpContentEncoder generates an empty chunk even if it's not the last chunk

- Fixes #1312
- Added more test cases to ensure the fix
update to barchart-udt 2.2.6
* which fix https://github.com/barchart/barchart-udt/issues/48
Simplify a bit