updateCriteria({radius: 0}) is ignored.

[AndrewKvalheim]

Noticed that updating the radius of a query to 0 doesn't have any effect on it:

var geoQuery = geoFire.query({center: [1,2], radius: 1000})

expect(geoQuery.radius()).toEqual(1000); /* passes */
geoQuery.updateCriteria({radius: 0});
expect(geoQuery.radius()).toEqual(0); /* fails */