Using Zero-Copy API to read.

1.Use ByteBuf based API to read.
2.Add a ByteBufferInputStream and make Chunk consume ByteBuffer directly.
The Zcopy.java file is from Gera's repository as a quick start. I'm using it to develop a quick prototype to show the ByteBuffer based reading really improves. I'll extract the related code from Zcopy.java and write a abstract layer after that.