Redirect to HTTPS and enable HSTS

[foolip]

Like https://github.com/w3c/wptdashboard/issues/128

[RByers]

+1. Especially now that Chrome is marking HTTP "Not secure". I find myself having to remember to manually add https:// prefixes to confluence URLs before I share them (for whatever reason, Chrome always sends me to the HTTP version when I rely on omnibox autocomplete to get to confluence in the first place).