Replace br_family filter

[keanerobinson]

Currently the following filter is applied in the page_views step of the model (see SQL:

WHERE a.br_family != 'Robot/Spider'

The br_family field is part of the user agent utils enrichment which is no longer set up by default for our web users. When the enrichment is enabled the br_ fields come up as nulls and the filter leads to the SQL creating an empty page_views table.

This filter should either be removed or replaced by another field.