SPDY: remove SPDY/2 support
Merge pull request #1921 from jpinner/kill_spdy_2

SPDY: remove SPDY/2 support
[#1920] Fix IndexOutOfBoundsException when using PooledByteBufAllocator with SCTP and NIO Datagram channels
[#1925] Only expose sub-region of ByteBuf on nioBuffer(...)
Run tests with Pooled and Unpooled allocator