Don’t require a specific jQuery instance for jasmine jQuery matchers

Signed-off-by: Max Brunsfeld <maxbrunsfeld@gmail.com>
Don’t assume SpacePen views implement ::unsubscribe

Signed-off-by: Max Brunsfeld <maxbrunsfeld@gmail.com>
:arrow_up: space-pen for interoperable $.fn.view method

Previously, the SpacePen view was associated with its elements
via $.fn.data, but this only works across a single instance
of jQuery. Now we store a ::spacePenView property as an expando
property directly on elements.

Signed-off-by: Max Brunsfeld <maxbrunsfeld@gmail.com>