added cancelEditObservation to get out of edit field; changed the way validateField is called -- it is now called anytime a field is changed, not when a field goes out of focus; added options to this.model.save function of saveObservation to alert the user when the server has an error; added validation that date can't be in futre or already entered; added final call to validateDate in saveObservation (depsite real-time validation, any field not changed won't be validated until a save)