Determine the default number of heap/direct arenas of PooledByteBufAllocator conservatively

- Fixes #1445
- Add PlatformDependent.maxDirectMemory()
- Ensure the default number or arenas is decreased if the max memory of the VM is not large enough.
[maven-release-plugin] prepare release netty-4.0.0.CR5
[maven-release-plugin] prepare for next development iteration
Don't release messages before throw UnsupportedOperationException, as the caller method will take care
Introduce new utility class calles ReferenceCountUtil and move utility methods from ByteBufUtil to it.

The ones in ByteBufUtil were marked as @deprecated
[#1448] Don't print failure if VoidChannelPromise is used
[#1450] Fix examples in ReplayDecoder javadocs
SPDY: better encapsulation of header encoding/decoding
SCTP: Reduce object allocation overhead and fix receive buffer allocation

There are a couple of changes here all related to making the SCTP
transport less garbage-heavy:

- Remove the SctpNotificationEvent and just passes along the JDK NIO
  Notification, as passing the Notification and always null inside a
  wrapped object seemed a little bit superfluous
- Apply @trustin's changes to receive buffer allocation to SCTP
  transport, and also makes the SCTP transport use the configured buffer
  allocator rather than always creating a direct buffer (which seems
  like a bug)
Upgrade to javassist 3.18.0-GA
Fix IllegalStateException triggered by a successful connection attempt

- Fixes #1467
- Provide more information about the tasks and promises on exception for easier debugging
Remove cruft
Make sure PlatformDependent.maxDirectMemory() works on Android

- Fixes #1451
Make sure PlatformDependent.isRoot0() works fine in Android

.. by swallowing ErrnoException raised by process.destroy().

Fixes #1472
Remove unnecessary logging handler - ByteLoggingHandler and MessageLoggingHandler / Extensible log message formatiing
Fix a compilation error
Fix IndexOutOfBoundsException raised by JZlibEncoder.encode()

- Fixes #1471
Fix checkstyle
Fix another compilation error
Make AbstractMemoryHttpData generate less garbage