time series scrubber movement does not span entire widget / data

Context

A partner / client needs a time series map off of data that is simply three years: 2012, 2013, 2014. They created a time series widget off of it and got the following:

Notice that the scrubber seems to have a different width than the underlying histogram.

related #12640

Steps to Reproduce

Same as in #12640:

1. Import this dataset with the same time properties as the client/partner data: http://eschbacher.carto.com/api/v2/sql?q=select * from time_series_issue_data&format=csv&filename=time_series_issue_data
2. Create a map for this data
3. Create a torque map and select the year column
4. Set number of steps to 3 (and reduce time to 6 so it goes more quickly)

Current Result

The following time series widget scrubber behavior:

Expected result

Scrubber spans the entire width

Browser and version

Chrome 60.0.3112.90 macOS 10.12.5

.carto file

CSV: http://eschbacher.carto.com/api/v2/sql?q=select * from time_series_issue_data&format=csv&filename=time_series_issue_data .carto file: time series widget three years (on 2017-08-23 at 16.24.54).carto.zip

Additional info

Comes from client / partner request

cc @timoco @jaime @zingbot

[noguerol]

This still needs a little bit of @CartoDB/design love

[arianaescobar]

IMO the scrubber should fall wherever the user clicks on the timeline (as it happens on a youtube video for example) and then it should keep moving forwards. I get that we are snapping filter handles to the limits of the buckets when we select them, but in this case, we’re not making any selection, we’re just moving along a timeline.

So, to clarify, the scrubber shouldn’t jump between each starting point, it should move along the full width of the bucket.