Hide apps if no collections exist

[asizemore]

Originally referenced here #706 (comment)

Let's prevent any collection-driven apps (all apps that i know of right now) from appearing on the page if the study has no collections.

This actually would be one possibility for unifying the clinepi/mbio viz tab pages because both clienpi and mbio like the grouping of vizs. Then clinepi just wouldn't see the apps since its studies have no collections.

[asizemore]

Alternatively we could gray out and just disable the apps, like we do for the map viz (the small one on the viz tab). That also would be nice.

[asizemore]

Closed with #732