Small docs fixes. Remove OkHttp 2 warnings.
Merge pull request #427 from square/jwilson_0109_more_docs

Small docs fixes. Remove OkHttp 2 warnings.
Update change log.
Fix a bug where discardStream took way too long.

We were relying on the socket timeout of a single read,
but performing multiple reads each with independent
timeouts.
Merge pull request #430 from square/jwilson_0111_timely_stream_discarding

Fix a bug where discardStream took way too long.
New CacheControl class.

This moves cache control headers from the main request
and response classes to their own class.
Merge pull request #431 from square/jwilson_0111_cache_control

New CacheControl class.
implement huffman decoding using code from twitter/hpack