Show 'loading, please wait' animation while database is downloading and loading

[abeconnelly]

It takes some time for the database to be loaded and unpacked. There should be a 'loading, please wait' animation that lets people know the data is loading and will be available soon. This animation should go away when the data is loaded.

[abeconnelly]

There might be a way to hook into the process that downloads data and have a JavaScript download progress bar.

[nro-bot]

locally, some strange effects of not having loading bar or static text about this: the query button says "g_db is undefined" and works on the second try (because it has had time to load), similarly the canned viz's show as blank on first try.

[abeconnelly]

g_db is the global variable used for the database context and so when trying to run a query when the database isn't loaded it gives this error. The canned visualization of course need the data loaded so there won't be anything to display.

There should be some checks to make sure the database is loaded and ready. All pages that use underlying database should have a 'loading' to make sure the user doesn't expect anything to happen until the load has completed.