Close the source after reading regardless of result.
Merge pull request #758 from square/jw/close-on-exhaust

Close the source after reading regardless of result.
Introduce Call for async invocations.
Merge pull request #761 from square/adrian.callmeanytime

Introduce Call for async invocations.
Add MockWebServerRule.
Merge pull request #755 from square/adrian.mwsrulez

Add MockWebServerRule
Use more convenience methods from Okio 0.8.0.
Merge pull request #763 from square/jw/okio-8

Use more convenience methods from Okio 0.8.0.
Merge Job into Call. CallTest = AsyncApiTest + SyncApiTest.
Merge pull request #764 from square/adrian.callfusion

Merge Job into Call. CallTest = AsyncApiTest + SyncApiTest
Throw CancellationException when blocking call cancelled as opposed to returning null.
Merge pull request #765 from square/adrian.blockingcall-cancellationexception

Throw CancellationException when blocking call canceled as opposed to returning null
Use IOE for canceled streams.
Merge pull request #766 from square/adrian.dont-split-hairs

Use IOE for canceled streams
Support common http verbs including zero length POST, DELETE.
Merge pull request #769 from square/adrian.common-verbs

Support common http verbs including zero length POST, DELETE.
Move more behavior into HttpEngine.followUpRequest