ui: consider simple mostly client-side wildcard filtering of tag values

[flyingmutant]

• The simplest thing: expand wildcards foo* -> [foobar, foobaz] in the selector (maybe server-side expand?), make matches easy to select with ui: "select all" checkbox for the selector #154.
• More complete solution: support wildcards in URLs, expand ~once (on the "page load"? or how often?) for more dynamic dashboarding/linking
• Server-side expand on each /api/query is probably too expensive (but maybe not overly, with api: tscache for tags #175?)