Add more mirrors

[seisman]

I have now sent reminder emails to UNAVCO and NOAA (Walter), plus asked the S. Africa FTP mirror folks if they would be able to serve data as well, and also Dietmar at U Sydney. Checking with @leouieda regarding S America - we have Eder doing the FTP mirror but not sure he has capacity. Once Leo responds I can send an inquiry that way as well. The main weakness today is North America but getting a unavco and noaa would go a long way (US east coast, US Mountain). Perhaps we can get Dave to host a us-west-coast mirror?

Originally posted by @PaulWessel in #18 (comment)

[leouieda]

Regarding S America, I think USP is the best place to host it. They probably have better infrastructure than anywhere else. I'm sure Eder would be glad to host. If not, the seismology group are heavy GMT users as well and have plenty of technical expertise (they host data servers for seismology).

(from #18)

[PaulWessel]

OK, I will start with Eder.