www/nextcloud port added

[Loïc BLOT]

Hi
nextcloud have many chances to replace owncloud as many owncloud
founders and developpers left owncloud company to create nextcloud
which is better for community.

I have ported nextcloud using owncloud port this morning.
Everything works well as the changeset from owncloud to nextcloud is
little.

https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=210295

Please commit asap for community :)

Thanks
-- 

Best regards,
Loïc BLOT, 
UNIX systems, security and network engineer
http://www.unix-experience.fr