- Combine all test init functions into `initConverse`
- Use `async` functions in more tests
- Replace `var` with `let` and `const` in more tests
- New utils method `toStanza` which converts a string to a Node
`toLocaleString` now returns element attributes in alphabetical order
(for better cross-browser consistency).
Also, `toLocaleString` is now used in favor of `outerHTML` because
browsers aren't consistent with one another in their output.