Update to curl 7.36.0

This version fixes a number of important security vulnerabilities:

* libcurl wrong re-use of connections - http://curl.haxx.se/docs/adv_20140326A.html
* libcurl IP address wildcard certificate validation - http://curl.haxx.se/docs/adv_20140326B.html
* libcurl not verifying certs for TLS to IP address / Darwinssl - http://curl.haxx.se/docs/adv_20140326C.html
* libcurl not verifying certs for TLS to IP address / Winssl - http://curl.haxx.se/docs/adv_20140326D.html