[#2021] No need to synchronize for unpooled chunks
Fix checkstyle
Optimize and clean up LoggingHandler

- Use ': ' instead of '(...)' for simpler string concatenation and prettier presentation
- Optimize the overall performance of format*() methods
- All format*() methods are now expected to encode the channel information by themselves so that StringBuilder instances are created less often.
- Use a look-up table for generating per-row prefixes
- Hid formatByteBuf(), formatByteBufHolder(), and formatNonByteBuf() from user because a user can always override format(ctx, eventName, arg).  For example, to disable hexdump:

    protected void format(ChannelHandlerContext ctx, String eventName, Object arg) {
        if (arg instanceof ByteBuf) {
            super.format(ctx, eventName, arg.toString());
        } else {
            super.format(ctx, eventName, arg);
        }
    }
Make LoggingHandler.appendHexDump(..) protected for the subclasses
Simplify two-args message formatter in LoggingHandler
Rename formatUserMessage to formatSimple and use it in two-args formatter in LoggingHandler
Improve documentation for the two-args formatter in LoggingHandler
codec-memcache: fix decoding issue for value parts.

This changeset fixes an issue when decoding would stop if the value
comes separated in two or more packets, leading to invalid bytes read.
codec-memcache: removed println in test case.
[codec-memcache] encode key directly, no need to use unpooled.
Merge remote-tracking branch: upstream/master