Export / Save Locally by query

[Webreaper]

Let's say you wanted to export all images with the tag "best". Currently, you'd have to search for 'best', then scroll down until you got bored of scrolling, and then add all the visible images to the basket.

A better solution would be akin to GMail's "Apply to all messages that match this filter". Implementation would be:

1. Create a SearchQuery object, cloned from the current search query in the search service.
2. Apply that with no first/last params to the search method.
3. Return all ImageIDs
4. Pass them to the export process.

Could componentize the search dialog, and re-use it at the top of the export page, so people could do custom filters, and see a preview of the first 10 images that match, and potentially an idea of how many results the filter would return (e.g., "this search will return more than 5,000 results... are you sure?".

This methodology would also work for the grouping issue #273 - the export would take the current search query, add the specific grouping (date/folder) and the execute the search with no first/last, and get all imageIds that match.