fix timeline - #36

@timwis - for when you're back, would like your review that it's ok to remove the basefilter. timeline chart wouldn't load with it included, but want to make sure it's not necessary before pushing live.

Is this working for you when you preview it on your computer? It looks like the to_date() function was in there previously, which suggests the field type in the database was a string rather than a date. The only way that wouldn't be necessary now, I imagine, is if the field type was changed (which would have required @Alexander-M-Waldman to change the schema file for the carto sync to work). But yes if it's working for you locally then I'd say good to go.