Improve filtering droplist UX

[rmouritzen-splunk]

The "n items selected" droplist next to the search box that exists on many screens. This is a filtering mechanism that has confused users in many cases. We want to make these settings more explicit.

Ideas:

• Move the filtering options to the left hand gutter so it is always visible.
• Change the HTML so the upper part of the page is always visible.

Keep mobile viewing in mind. The left hand gutter, for instance, doesn't show up at all on mobile browsers (at least not on iPhone). Keeping a portion a page always visible could make mobile viewing more difficult with a large percentage of the visible view locked in place.