Revert "PLAT-783: HttpClient and HttpClientImpl no longer an AsyncEventSource"

This reverts commit 851416254c09dea19e074660329636cbd42af1a3.
service_base: corrected typos and set limit to 65535
added epoll_wait test bench
PLAT-792 - Num values properly stored as nums

commit fc32eaeff7b6baa70daf91efb18a1d5066f5ffc8
Author: Mich <fmlheureux@datacratic.com>
Date:   Wed Dec 17 16:21:13 2014 -0500

    Removed useless struct Holder, fixed bogus err msg

commit b8d5e060d5e3f0d6bffcb8c8050f9e9ba6d37545
Author: Mich <fmlheureux@datacratic.com>
Date:   Wed Dec 17 11:12:37 2014 -0500

    PLAT-792 fixed terminal output

commit 19ca6a57448db14bfabfd27f349a9c638d3b70e8
Author: Mich <fmlheureux@datacratic.com>
Date:   Wed Dec 17 11:09:14 2014 -0500

    PLAT-792 proper numeric values support from json

commit 6075af0d7e88e8d709420198b45ac3eb87ef9274
Author: Mich <fmlheureux@datacratic.com>
Date:   Tue Dec 16 17:29:33 2014 -0500

    PLAT-792 numbers are logged as numbers on direct value

commit cdb9221d17b82bb2a413f990dcd767dbc5b8c7b7
Author: Mich <fmlheureux@datacratic.com>
Date:   Tue Dec 16 16:55:12 2014 -0500

    Improved mongo test with mongo server
Fixed online test
HttpClient: disable 'Expect: 100 Continue' from all impls
Revert "PLAT-783: adapted HttpClient v2 to new interface"

This reverts commit 487a6f601f59c129f8f9a2008ce05df5ff39ec53.

Conflicts:
	service/testing/http_client_test.cc
Merge branch 'master' into http-client-ih

Conflicts:
	service/testing/http_client_test.cc
Backported changes from v3
fixed parent classes
fixed http client test