Limit shapely version.
Limit shapely version.

New versions don't play well with cartopy, until cartopy 0.13.1 which
isn't on pypi yet.

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