Vis options panel

Built off of #1763 (merge that PR first)

Closes #1618 

This PR adds visualization options to allow for disabling elements (legend, tooltip) as well as custom vis options (like **mode** for histogram).

- `params` are set on a vis_type, including defaults and an editor
- The editor is used for the UI for setting the associated options
- The new renderbots (introduced in #1763) can now have their params refreshed

@spenceralger you seemed bothered by this, so I wanted to point it out. I think you were advocating just putting them in the editor template, no? I like having the definitions in the vis_type because it keeps the settings in one place.