Correct gs: and gcs: file protocols for name scripts

[jameshalgren]

Suggest the following correction (items #5 and #6) to allow for proper downloading:

urlbasedict = {
    0: "",
    1: "https://nomads.ncep.noaa.gov/pub/data/nccf/com/nwm/prod/",
    # TODO The post-processed data will need its own name generator, such as
    # we have made for the retrospective data.
    # 2: "https://nomads.ncep.noaa.gov/pub/data/nccf/com/nwm/post-processed/WMS/",
    3: "https://storage.googleapis.com/national-water-model/",
    4: "https://storage.cloud.google.com/national-water-model/",
    5: "gs://national-water-model/",
    6: "gcs://national-water-model/",
    # TODO: add Amazon output??
    # 7: amazon s3 operational output
    # 8: amazon https operational output
}

(The todo associated with #2 and #7 is for another issue.... link forthcoming)

[jameshalgren]

@RohanSunkarapalli