Options format inside option_definition() method is out of date

Options array inside option_definition() method uses a pre-2 Views.module format.

In Views version 2 (and beyond) this means that options defaults are effectively skipped during options form constructions. In turn, this leads to (in)famous invalid argument to foreach.. during form display, because, for instance, to 'checkboxes' widget NULL is passed instead of empty array().

Hope the patch speaks for itself.