Tests and docs updates for OkHttp update.

OkHttp has made various changes. This fixes the known
breakages before the update is applied.

1) Chunk length is no longer honored exactly. The
API docs have been updated to reflect this.

2) testConnectViaHttpsWithSSLFallback simulated an SSL
handshake failure by closing the socket. This is no longer
sufficient to trigger the fallback behavior after OkHttp change
46a0852. testSslFallback tests an actual handshake failure and
provides coverage. testConnectViaHttpsWithSSLFallback
has therefore been removed.

3) testRetryableRequestBodyAfterBrokenConnection is similar to
testConnectViaHttpsWithSSLFallback. Previously it passed because
of the SSL fallback behavior. That fallback no longer happens.
It is possible this was actually supposed to be checking the
internal RetryableOutputStream. Now OkHttp does not retry
connections after the connection is made it is not possible
to test the request body is "replayed" to the server.

4) testNonRetryableRequestBodyAfterBrokenConnection: Related to
3 above. It was testing that fixed length request bodies are not
retryable. This test continues to pass with OkHttp but only
because it fails to retry generally, not because of the request
body and therefore the test is misleading.

Change-Id: If430bce75ad5b2fd5ace38d0f65d9c4af56b88df
2 files changed