Production Release 8/4/2021

release 20210804 (#377)

* add auto-scroll button to river table on mobile

* move map table scroll indicator to bottom of map table

* create rapid image picker interface and modal workflow

* implement paging for image selector modal

* pass rapid image as already selected image to image selector modal

* add business logic for updating photo on rapids

* fixes two client-side issues. one formatting and the other with gauge priority when there is an old reading summary.

Co-authored-by: Nick Gottlieb <ngottlieb@gmail.com>
Co-authored-by: Matt Anger <matthew.anger@gmail.com>