Always define namespace for record elements

Changed toXML to make sure when it is render both with and without a
collection element that the MARC namespace is present.

Signed-off-by: Dan Scott <dan@coffeecode.net>
Update tests to match record namespace declaration

Signed-off-by: Dan Scott <dan@coffeecode.net>
Prep for 0.7.3 release

Signed-off-by: Dan Scott <dan@coffeecode.net>