package/nmap: bump version to 7.60

Version 7.60 added optional support for libssh2:
http://seclists.org/nmap-announce/2017/4



Switched _SITE to https

Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>