This change refactors out the plugin code from converse-core into
src/converse-puggable.js
Additionally, plugins now have an optional attribute `optional_dependencies`
which is an array of dependencies which are "nice-to-have" but not essential.
Work has also been done to ensure that a plugins' dependencies are first loaded
before the plugin itself.
Couldn't handle messages with no "from" attribute.
Some refactoring to add code that checks if a messages is a headline to the
utils module.
Updated tests. Add sinon so that we can test returned value of spy.
In the process refactored the code being tested.
- Move notifications code in MUC to src/converse-notification.js
- Trigger the 'contactStatusChanged' event in RosterContact and not in
ChatBoxView (which might not exist).
prevous fix wasn't correct. Rename handlers to make it clear which methods are
the event handlers, put them together and make sure docstrings are relevant.
