Add colortables from NEXRAD ICD.
Add colortables from NEXRAD ICD.

ahaberlie/MetPy,jrleeman/MetPy,Unidata/MetPy,deeplycloudy/MetPy,dopplershift/MetPy,jrleeman/MetPy,ShawnMurd/MetPy,ahaberlie/MetPy,ahill818/MetPy,Unidata/MetPy,dopplershift/MetPy