ENH: BigQuery backend should default / to IEEE_DIVIDE

[tsdlovell]

else you can get a failure regarding divide by zero in the middle of your query execution

https://cloud.google.com/bigquery/docs/reference/standard-sql/functions-and-operators#special-cases-for-ieee_dividex-y

In [1]: import ibis

In [2]: client = ibis.bigquery.connect('project_id', 'dataset_id')

In [3]: client.raw_sql('select 1 / 0')
---------------------------------------------------------------------------
BadRequest                                Traceback (most recent call last)
<ipython-input-3-1e33b273ef6c> in <module>()
----> 1 client.raw_sql('select 1 / 0')
...
BadRequest: 400 POST https://www.googleapis.com/bigquery/v2/projects/project_id/queries: division by zero

In [4]: client.raw_sql('select IEEE_DIVIDE(1, 0)').fetchall()
Out[4]: [(inf,)]

[cpcloud]

Seems reasonable.