Validate curl 7.59 fix for chunked encoding

[djones6]

Kitura/Kitura#1465 was raised to track a bug in curl relating to receiving a response with a chunked encoding, which broke in curl 7.57 and was fixed in curl 7.59, but which is shipped in Ubuntu 18.04 (ships curl 7.58).

We need to validate that the 7.59 fix does actually resolve the problem we have with ClientRequest and the duplicate callbacks.

[djones6]

Another thing to check: what happens if we build the server in KITURA_NIO mode? Kitura-NIO doesn't use curl, so this may be a workaround of sorts.

[djones6]

@RudraniW I believe that @wbittles did complete this and we established that the fix in curl 7.59 resolves the bug. But you could recreate yourself locally which may help in testing the toleration changes for Kitura-net.