ENH: Shift doc build to 3.5
ENH: Shift doc build to 3.5

This is the last of our core on Python 2, and there's no good reason for
it.

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