Use AOSP ByteArrayPool to try and avoid buffer GC.

Re-using buffers can help avoid GC and make things run more smoothly when streaming data.

squash! Use AOSP ByteArrayPool to try and avoid buffer GC.

Copy tests over and attempt at better formatting.

squash! Use AOSP ByteArrayPool to try and avoid buffer GC.

ArrayDeque is <= API level 9 :-(

squash! Use AOSP ByteArrayPool to try and avoid buffer GC.

Another attempt at formatting.

fixup! squash! Use AOSP ByteArrayPool to try and avoid buffer GC.

Indent code properly attempt.
Another round of header APIs cleanup.

This promotes Headers to a public API from the internal package.
It moves some of its methods to OkHeaders, which has been renamed
from SyntheticHeaders.

Making the Headers class public API makes it possible to remove
more exotic APIs from Request and Response like the APIs to track
headers by index rather than by name.
Merge pull request #394 from square/jwilson_0102_headers_apis

Another round of header APIs cleanup.
add read response header timeout case
timeout issue
Merge pull request #397 from lingmingyb/timeout_test

add read response header timeout case
Merge pull request #398 from lingmingyb/timeout_issue

timeout issue
update http2 to draft 9 and hpack to draft 5
Only Java 6 and up are supported now.
Merge pull request #401 from square/jw/one-six

Only Java 6 and up are supported now.
Implement simple limits in the dispatcher.

This adds Dispatcher to the public API so that application
code can tweak the policy.
Merge pull request #396 from hwrdprkns/avoid_buffer_gc

Use AOSP ByteArrayPool to try and avoid buffer GC.
Merge pull request #400 from adriancole/http2-draft09

update http2 to draft 9 and hpack to draft 5
Merge pull request #399 from square/jwilson_0104_dispatcher

Implement simple limits in the dispatcher.
Change SpdyStream to be safe for any initialization order.

Previously we were assuming a field initializer wouldn't be
run until after the constructor. It wasn't and we were getting
NullPointerExceptions looking up the bufferPool.
Tests for canceling async requests.
Merge pull request #406 from square/jwilson_0105_order_of_init

Change SpdyStream to be safe for any initialization order.
Merge pull request #407 from square/jwilson_0105_cancel

Tests for canceling async requests.
address comments from issue #400
Merge pull request #408 from adriancole/http2-draft09-comments

address comments from issue #400