Charm browser defaulting to open

[Benji York]

While doing the QA for the most recent Juju GUI release, I noticed that
the charm browser is visible by default.

I suspect this is intended to make the user aware of the charm browser's
existence but I strongly suspect that the first thing a long-term user
of the GUI will do when launching the app is to close the browser.
(While muttering under their breath.)

Perhaps we can ameliorate the issue by recording the open/close state of
the charm browser in the web browser's sessionStorage.
-- 
Benji York