Outdated Docker image for Travis CI

Based on the checks on #92, it looks like our current CI is running into issues with intake-esm single file catalogs:

=================================== FAILURES ===================================
__________________ test_get_intake_source[climate.GFDL_CM2_6] __________________
catalog = <Intake catalog: master>, dataset_name = 'climate.GFDL_CM2_6'
    def test_get_intake_source(catalog, dataset_name):
        item = catalog[dataset_name]
>       if item.container == "catalog":
tests/test_datasets.py:23: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
/srv/conda/envs/notebook/lib/python3.7/site-packages/intake/catalog/entry.py:121: in __getattr__
    return getattr(self._get_default_source(), attr)
/srv/conda/envs/notebook/lib/python3.7/site-packages/intake/catalog/entry.py:93: in _get_default_source
    self._default_source = self()
/srv/conda/envs/notebook/lib/python3.7/site-packages/intake/catalog/entry.py:78: in __call__
    s = self.get(**kwargs)
/srv/conda/envs/notebook/lib/python3.7/site-packages/intake/catalog/local.py:283: in get
    data_source = plugin(**open_args)
/srv/conda/envs/notebook/lib/python3.7/site-packages/intake_esm/core.py:70: in __init__
    self.df = self._fetch_catalog()
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
self = <[RecursionError('maximum recursion depth exceeded while calling a Python object') raised in repr()] esm_datastore object at 0x7fbbbd42b4e0>
    def _fetch_catalog(self):
        """Get the catalog file and cache it.
        """
>       return pd.read_csv(self._col_data['catalog_file'])
E       KeyError: 'catalog_file'

Is there a more recent Docker image we could pull that has an updated intake-esm?

pangeo-data / pangeo-datastore

Outdated Docker image for Travis CI #93