Add visualizations for institutions and overall number of repositories

[roblesjoel]

1. On institution detail view, add several visualizations of key numbers (contributors etc.). The diagrams should be ordered in a new tab of the detail view: https://material.angular.io/components/tabs/overview First tab are the diagrams, second tab is the table of the orgs and repos.
2. On the landing page (see red box on screenshot), add an overview visualization with several graphs (growing number of institutions, orgs, repos etc.)

[roblesjoel]

What data should be visualised and how @maemst?