add saved lists to landing page for returning users

[wholmgren]

The landing page help text is good for new users, but returning users would benefit from something more useful. Perhaps users could star or otherwise save particular sites, aggregates, forecasts, observations, or reports and those would show up in one (or more) lists. So then I just go to dashboard.solarforecastarbiter.org and can immediately click on the links to the things I care about the most.

Seems like it would take a good bit of effort to do this right, so I'm not expecting we'll get to it anytime soon (or ever).