Add 'pause' to vacancy status

Currently you have to change vacancy status to internal or draft if you want to pause getting more candidates coming through. This doesn't work particularly well and 'pause' is what you are really wanting to do. This makes it quick and easy to see what vacancies are physically paused - the vacancy isn't in draft, it's already been online and can be easily confused by a vacancy that is being considered but has not yet been signed off and internal equally is misleading