data_obs_client examples and fixes

[alrocar]

While running the darta_obs_client examples I found out this error:

TypeError                                 Traceback (most recent call last)
<ipython-input-4-26a14e86748a> in <module>
----> 1 es_boundaries = do.boundaries(region='Spain')
      2 es_boundaries.dataframe[['geom_name', 'geom_id']]

~/Documents/dev/cartoframes/cartoframes/data/clients/data_obs_client.py in boundaries(self, boundary, region, decode_geom, timespan, include_nonclipped)
    198                     timespan=utils.pgquote(timespan),
    199                     filters='WHERE {}'.format(filters) if filters else '')
--> 200             return self._fetch(query, decode_geom=True)
    201 
    202         query = utils.minify_sql((

TypeError: _fetch() got an unexpected keyword argument 'decode_geom'

cc. @Jesus89 for triage

[Jesus89]

This is a quick (and necessary) fix. We can review also the DO v1 e2e tests which are not up to date.