The problem was that the `emojisInitialized` promise was re-created upon
logout and then no longer resolved upon subsequent login.
The `_converse.api.promises.add` method now takes another parameter
`replace` which determine whether it should be replaced upon logout or
not.
The `emojisInitialized` promise will now not get replaced.
Depend on latest backbone.browserStorage which has support for IndexedDB
via localforage.
Storage operations are now asynchronous and transactional.
Bugs fixed (mostly by waiting for operations to complete):
* Rooms are now fetched asynchronously, so wait before triggering `show`
or when closing.
* Make sure chat create/update transactions complete before firing events
* Make sure chats and messages have been fetched before creating new ones.
* When doing a `fetch` with `wait: false` on a collection and then
creating a model in that collection, then once the read
operation finishes (after creating the model), the collection is emptied again.
* Patch and wait when saving.
Otherwise we have previously set attributes overriding later ones.
* Make sure api.roomviews.close returns a promise
Test fixes:
* Chats are now asynchronously returned, so we need to use `await`
* Wait for the storage transaction to complete when creating and updating messages
* Wait for all chatboxes to close
Otherwise we get sessionStorage inconsistencies due to the async nature of localforage.
* Wait for room views to close in spec/chatroom.js
In the process, remove the `closeAllChatBoxes` override in
converse-controlbox by letting the `close` method decide whether it
should be closed or not.
