Fixes for Python 2.
Fixes for Python 2.

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