add more grads-servers

[df8oe]

NOAA is nearly complete inaccessible since a week. I think there are much more grads-dods-servers - may be with slightly different paths and/or ports. To improve the stability it is a good thing to have access to more than one data source. For a quick hack the different sources can be activated/deactivated in predict.py via removing comment-signs... Ports can be a part of a variable "host" as paths, too. So there can be a list of possible servers at the top of the script where a running one can be choosen.

Andreas