Add confirmation message if the current Master Company is unchecked

Add a confirmation message if the user unchecks the Master Company checkbox on the Multi-Company Mgt. Page. The confirmation message will say:

Are you sure you wish to disable Company X as the master company? If no master company is specified then the syncing functionality will not run and companies can become out of sync. If you do not want to use the syncing functionality going forward, please uninstall the extension.