fix tests

The tests were using blessed() without importing it from
Scalar::Util. I used the basic ref() instead.
Fix Search->next()

The next() method in the Cursor class is returning an arrayref,
which was not playing nicely with the inflation of the objects.
Merge branch 'search-next' of git://github.com/yanick/DBIx-NoSQL
Update to version 0.0020