Don't suggest NPN will be used when it might be ALPN.
Rename execute to enqueue for async calls.

I prefer 'enqueue' because we might not actually run the job
for some time (due to dispatcher's limits).
Small cleanups.

Return the OkHttpClient on setters.
Remove some completed TODOs in Call.
Link to Okio in Javadoc.
Merge pull request #779 from square/adrian.remove-npn-tagging

Don't suggest NPN will be used when it might be ALPN
Merge pull request #780 from square/jwilson_0427_rename_execute

Rename execute to enqueue for async calls.
Merge pull request #781 from square/jwilson_0427_tiny_cleanups

Small cleanups.
Add ALPN support; Configure maven to use ALPN on OpenJDK 8.
Merge pull request #687 from square/adrian.death-to-npn

Add ALPN support; Configure maven to use ALPN on OpenJDK 8.
Change HttpResponseCache to not implement java.net.ResponseCache.

This marks some methods as @Deprecated and internal-only.
Unfortunately we don't have a great mechanism to hide them from
the documented API.
Merge pull request #784 from square/jwilson_0428_cache_interfaces

Change HttpResponseCache to not implement java.net.ResponseCache.
Rename HttpResponseCache to Cache.

Also move OkResponseCache.java into internal.
Merge pull request #785 from square/jwilson_0428_rename_cache

Rename HttpResponseCache to Cache.
New approach to hiding implementation details.

This relies on the happy accident that OkHttpClient.class will be initialized
before any attempt to use internal APIs.
Merge pull request #786 from square/jwilson_0430_hide_implementation_details

New approach to hiding implementation details.
Hide more APIs with Internal.access.

The callsite is uglier but the API is neater. I think overall
it's a small win.
Merge pull request #788 from square/jwilson_0430_hide_more_apis

Hide more APIs with Internal.access.
Hide ConnectionPool.recycle and share.
Merge pull request #790 from square/jwilson_0430_hide_hide_hide

Hide ConnectionPool.recycle and share.
Use Okio for timeouts in SPDY.

This depends on new AsyncTimeout API in Okio being released.