Allow public dashboards

Dashboards can now be marked as publically visible in the user
preferences. The dashboard URL has changed from /user/<name>/dashboard
to /dashboard/<name> because /user/<name> requires being logged in as
<name> or as an admin.

src/sql/upgrade-49.sql

@@ -0,0 +1 @@
+alter table Users add column publicDashboard boolean not null default false;