Allow queries to be printed about cqengine HOT 2 CLOSED

Fixed in trunk.

The code:

    Query<Car> query = and(
        equal(Car.MANUFACTURER, "Toyota"),
        equal(Car.COLOR, Car.Color.BLUE),
        equal(Car.DOORS, 3)
    );

    System.out.println(query);

Now prints:

    and(equal(Car.manufacturer, Toyota), equal(Car.color, BLUE), equal(Car.doors, 3))

The toString representation of queries, now resembles the representation of 
those queries in code (i.e. as constructed using QueryFactory). There is still 
some work to be done for toString representation of JOINs.

I'll leave this ticket open until this fix has been released to Maven central.

Implemented the remaining changes to support toString for JOINs.

Released in CQEngine 1.2.1.