Updated link to open source license
Merge remote-tracking branch 'origin/1.7' into 1.8

Conflicts:
	lib/Sabre/CalDAV/includes.php
	lib/Sabre/CardDAV/includes.php
	lib/Sabre/DAV/Exception/FileNotFound.php
	lib/Sabre/DAV/includes.php
	lib/Sabre/DAVACL/includes.php
	lib/Sabre/HTTP/includes.php
More updated license urls.