add badge icon/color/indicator to visit table view for missing visit_task or task files

[WillForan]

We need to indicate which checkedin visits in the visit table have missing visit_task data.
Upon check in, visit_task measures should be set to null, and then iteratively filled in.

Visits view should indicate which visits still need measures values for any corresponding visit_task rows (unless the checkedin visit is marked as dropped).

Additionally, some tasks specify files to be collected. We should make a count of that too (#34)

Data could come from:

1. changing the visit_summary view in pgsql and the corresponding python code to include a count of visit_task.meassures is null and visit_task.files is null and task.file is not null OR
2. each type we display visits, query each row's vid, and do the count there. -- we will at least need a button/menu option to do this for just the file check

Display could be:

1. a new badge column with icon/text about what is missing or all good
2. coloring visit rows to indicate checkedin measures and files status