Cleaning up the Download options

- EDB installers are up to date.

- BigSQL installers are up to date.

- postgres.app is up to date.

- Fink is a release behind on 9.4 through 10, and doesn't carry 11 at all as far as I can tell.

- MacPorts is up to date.

- The Homebrew link seems to go to a download site which after many clicks gives me the Windows installer from EDB(!). I've fixed that now. The packages appear to be a release behind on all supported branches.

Thoughts on whether we should make any changes to the Fink and Brew distributions? We used to require that the primary downloads be maintained on our schedule, so by rights they should be removed.

Secondary (third party) downloads:

- LiveCD - this hasn't been updated since 9.6 in December 2016. It should be removed.

- 2UDA - This hasn't been updated since May 2018, and is currently carrying 11beta1, 10.4, 9.6.9 and 9.5.13. I think this should be removed.

- TurnKey - Deploying this requires signing up to their service. I eventually tracked down the manifest file for their images and found they ship 9.4.6. This should be removed.

- BitNami images are up to date.

Comments etc? I'm out from EOD until Tuesday, but will review any comments somewhen after then, and make changes as appropriate (including following my own suggestions if noone disagrees with them :-p ).