Move connect to be closer to connection.

This eliminates some awkwardness in OkHttpClient, where it needs
to make a bunch of internal calls to Connection.
Merge pull request #972 from square/jwilson_0628_move_connect

Move connect to be closer to connection.
Added tests for hpack.

Issue square/okhttp#931

244 passed, 264 failed.
Merge remote-tracking branch 'upstream/master'
Merge branch 'master' of https://github.com/westarle/okhttp