create a banner with an end date for migrated sites

[kayiwa]

We recently created https://library-migrated.lib.princeton.edu and fpul-migrated.lib.princeton.edu

Could we please create a banner announcing a day when these VMs and domain will actually be shut down. It is my hope that they will not be supported in perpetuity.

[kevinreiss]

We can post an alert on the sites Francis. The plan is to keep them up for the rest of the year. However I plan to check back in a few weeks to see if we can do it sooner.

[kevinreiss]

Banners are updated. Had to update base_url values in princeton to ensure special collections displayed properly on library-migrated.