Null Ref and Missing using statement

Null exception if value is null
Changed double if statements in ValidatesPresenceOf into an if/else statement, because if the value is null it would through a NullReferenceException when it called ToString on it.

In ValidateIsCurrency added a return after value == null check is true as we don't need to process the rest of the method and if you did and value was null he ToString call would throw a NullReferenceException.

Missing using statement
Using statement is missing, this should be disposing the reader when done. It is in sycn with the other Query method now as well.