adding setVerifyPeer() to enable/disable SSL peer verification

Conflicts:
	lib/Sabre/DAV/Client.php
adding setVerifyPeer() to enable/disable SSL peer verification
unit test added
fixing unit test
Fixing unittest for 1.6
Updated changelog
Merge branch '1.6' into 1.7

Conflicts:
	lib/Sabre/DAV/Client.php
Merge branch '1.7' into 1.8
Fixed unittest for 1.8