No longer advertising VCARD 4.0 support.
Merge branch '1.6' into 1.7

Conflicts:
	ChangeLog
	lib/Sabre/CardDAV/Version.php
	lib/Sabre/DAV/Version.php
Merge branch '1.7' into 1.8

Conflicts:
	ChangeLog
	lib/Sabre/CardDAV/Version.php
	lib/Sabre/DAV/Version.php