dataset.remote_access(use_xarray=True) broken by xarray v0.14

[zbruick]

With xarray v0.14 and siphon v0.8, when one calls

dataset.remote_access(use_xarray=True)

it now returns a traceback of:

----> 1 ds = dataset.remote_access(use_xarray=True)
925
926~/miniconda/envs/unidata/lib/python3.7/site-packages/siphon/catalog.py in remote_access(self, service, use_xarray)
927    620             raise ValueError(service + ' is not a valid service for remote_access')
928    621 
929--> 622         return self.access_with_service(service, use_xarray)
930    623 
931    624     def subset(self, service=None):
932
933~/miniconda/envs/unidata/lib/python3.7/site-packages/siphon/catalog.py in access_with_service(self, service, use_xarray)
934    672         if service == 'CdmRemote':
935    673             if use_xarray:
936--> 674                 from .cdmr.xarray_support import CDMRemoteStore
937    675                 try:
938    676                     import xarray as xr
939
940~/miniconda/envs/unidata/lib/python3.7/site-packages/siphon/cdmr/xarray_support.py in <module>
941      7 from xarray.backends.common import AbstractDataStore, BackendArray
942      8 from xarray.core import indexing
943----> 9 from xarray.core.utils import FrozenOrderedDict
944     10 
945     11 from . import Dataset
946
947ImportError: cannot import name 'FrozenOrderedDict' from 'xarray.core.utils' (/home/travis/miniconda/envs/unidata/lib/python3.7/site-packages/xarray/core/utils.py)

Looks like FrozenOrderedDict was renamed in pydata/xarray#3389 to FrozenDict.