Fix travis config.
Fix travis config.

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