This causes an empty bookmarks list in the controlbox, because the
collection gets cleared (and then asynchronousy repopulated) while the
`bookmarksInitialized` promise stays `true` (resulting in a race
condition).
Alternative fix could be to clear the bookmarks and recreate the promise
before reconnecting but doesn't seem necessary to do all that work.
- Update to the latest @converse/skeletor (which uses mergebounce to batch writes)
- Flush storage before logging out
- Flush when reloading the tab
- Create initStorage method
