Calibration quality check

[nhurleywalker]

We should perform a calibration quality check before applying the calibration solutions. If the calibration is not of the required quality then the autocal script should exit with an error so that applycal is not run. Ideally we would also automate the application of good calibration solutions from the nearest-in-time highest-S/N observation. This will almost certainly need to be run as a second pass in order to ensure that the solutions have actually been generated by the time they are required.