Some tests were failing on my box because I've got my locale set to
Portuguese; this shouldn't be an issue, since the NanoDB tests are
explicitly written in English. In order to fix Date parsing language-
agnostically, I just explicitly set the locale to `Locale.ENGLISH`.

The Buffer Manager wasn't tied into the property-registry mechanism,
so it wouldn't notice when the page-cache size was changed.  This is
now hooked together with a property-observer interface.