HTTP/2 Data Decompression

Motivation:
The HTTP/2 codec does not provide a way to decompress data. This functionality is supported by the HTTP codec and is expected to be a commonly used feature.

Modifications:
-The Http2FrameReader will be modified to allow hooks for decompression
-New classes which detect the decompression from HTTP/2 header frames and uses that decompression when HTTP/2 data frames come in
-New unit tests

Result:
The HTTP/2 codec will provide a means to support data decompression
Seems like a good approach.

@nmittler - I know we have talked about this before.  I'll open an issue to re-view the HTTP/2 unit tests because I feel like this is wide spread.