A rollup of recent upstream commits for OkHttp

squareup/okhttp commits from:
0a197466608681593cc9be9487965a0b1d5c244c
to:
b609edd07864d7191dcda8ba1f6c833c9fe170ad

squareup/okio commits from:
654ddf5e8f6311fda77e429c22d5e0e15f713b8d
to
82358df7f09e18aa42348836c614212085bbf045

Changes that might affect Android:
1) Cache control request headers: If-None-Match
or If-Modified-Since sent, never both.
2) Make okhttp behave more like a private, not a
shared cache.
3) SSLPeerUnverifiedException now thrown on
hostname verification errors, not IOException.

Change-Id: I3a2e8ae9bebfec84eaf8eb2aaa70085fa40fadd5