Switch-db-tray does not work with query options

This fixes a problem where using the db tray switch shows incorrect
results. To confirm fix:
1. Open a database (database A) and search for a single key with the
queryoption-tray: you get one document as result
2. use the new tray to switch to another database (database B)
3. you should see that all_docs from database B now shows up as you'd
expect

Closes COUCHDB-2460