dockerhub's official gcc images have fortran support now so we can use them!

Dockerfile

 # This image creates a common scientific build environment that includes:
 # gfortran, hdf4, hdf5, netcdf4
 
-# NOTE: nbearson/gfortran is a modified version of the official
-# docker gcc image that includes gfortran. Now that the official
-# image also includes gfortran, this line should change once a new build
-# of the gcc image is pushed to dockerhub.
-# to...
-# FROM gcc
-FROM nbearson/gfortran
+FROM gcc:latest
 
 ENV ZLIB_VERSION 1.2.8
 ENV JPEG_VERSION 6b