Allow generating metatype xml at version 1.2

Allow suggesting that metatype resources be generated from spec annotons into the 1.2 namespace.

The flag that allows this is preferV12.  This also switches the tests to use the XmlTester class and makes a Designate document generated from a DS component be a valid metatype resource.

Signed-off-by David Jencks <david_jencks@yahoo.com>