Perform the video summary on the client with configurable thresholds

[l2fprod]

The API "/api/videos/:id" in web/app.js performs the filtering of keywords/tags/faces to build the video summary. It ends up providing a static view for a video as the thresholds and minimum count are configured in app.js.

Instead we could return the full data to the client and have the threshold configurable in the client. This way one could play with knob-like controls to show more/less data.