Support the GFS apcpsfc variable

[deckerego]

Likely will require a modification to nickginsberg/noaa-gfs-js

See also:
http://gradsusr.org/pipermail/gradsusr/2016-May/039793.html
https://publicwiki.deltares.nl/spaces/FEWSDOC/pages/238191447/How+to+import+GFS+accumulative+precipitation

[deckerego]

Supposedly all available fields from https://nomads.ncep.noaa.gov/ are available in the library