Be able to filter by multiple potential actions

[jdudley1123]

Suggestion from Annie.

Short term, we could replace the search box with checkboxes.

Medium term this will probably get too big, so we could replace it with a multiselect autocomplete box (like you would have for tags - possible implementation here)

Long term we might want to go as far as some kind of structured query approach - to allow complex filtering like 'attended hop and candle but didn't use Nesta form'