Force install of ncepgrib2 if installing pygrib

Added logic to setup.py to added ncepgrib2 to packages_to_install list
if pygrib was listed to install.  ncepgrib2 is a dependency for pygrib.

setup.cfg.template

@@ -2,8 +2,8 @@
 # build options. 
 # Follow instructions below for editing.
 [install_options]
-# Provide a list of packages to install ("pygrib" or "ncepgrib2"). Both
-# can be provided.
+# Provide a list of packages to install.
+# IMPORTANT: If installing pygrib, then ncepgrib2 must be installed as well.
 #packages_to_install = []
 [directories]
 # uncomment and set to grib_api install location.

setup.py

@@ -81,6 +81,11 @@ def getq(self, s, k, fallback):
 grib_api_libname = config.getq(
     "files", "grib_api_libname", 'grib_api')
 
+# Force ncepgrib2 in list if installing pygrib.
+if "pygrib" in packages_to_install and \
+   "ncepgrib2" not in packages_to_install:
+    packages_to_install = ["pygrib","ncepgrib2"]
+
 libraries=[]
 libdirs=[]
 incdirs=[numpy.get_include()]