Shared dashboard footer should be always aligned to the bottom

[arikfr]

When loading a public dashboard, before there is content to show, this is what the user sees:

1. We need to align the footer to the bottom, even when there is no content.
2. Add some loading indicator.

[ranbena]

Is this happening in current master? How do I repro?

[arikfr]

Yes. To reproduce you either add a delay in the time it takes to load a dashboard, or just comment out the following line:

redash/client/app/pages/dashboards/public-dashboard-page.js

Line 62 in 51d8131

this.refreshDashboard();