Initial commit of expect 100-continue support
Also support HTTP with expect 100 continue

This creates an HTTP (not HTTPS) subclass and just
copies the class dictionary of the HTTP method overrides
into the HTTPS subclass.  Added an integration test for this
as well.
Fix failing tests
Fix py3 test failure
Reset response class when not handling expect 100 continue
Remove check for service name in s3

This can never happen because we subscribe to a specific
s3 event.  This was mentioned in code review feedback.
Merge branch 'expect-100' into develop

* expect-100:
  Remove check for service name in s3
  Reset response class when not handling expect 100 continue
  Fix py3 test failure
  Fix failing tests
  Also support HTTP with expect 100 continue
  Initial commit of expect 100-continue support