Update Database's createQuery() to return an error or throw CouchbaseLiteException (Beta 3)

While looking at the API and Jay's in-progress PR related to LiveQuery, I started to think that we should have the method throw an exception or return an error right away if the N1QL string cannot be parsed. Currently we defer the returning error to the execute method BUT this means that if the user is using LiveQuery alone, there will be no error returned when N1QL string is wrong.