Log Message:
ykclient: update to 2.15

* Version 2.15 (released 2015-11-12)
** Add ykclient_get_server_response() to the library.
** Show more information from the commandline on debug.
** Add proxy support via Curl.

* Version 2.14 (released 2015-03-05)
** Switch default templates to https.
** Fixup call to curl_easy_escape() to use a easy handle.