Date range selector should display the date range for the past week by default

[nichhk]

Overview

In PR #1268 , we changed the dev site to get data from the past week by default. However, this is not reflected in the DateSelector--it just says "Select a date range". This should be updated.

Action Items

• I'm not quite sure where this change is supposed to go right now, but it would be somewhere in here or one of the React components that it uses. We can search for "Select a date range" in our repository and see which component is using that string as a default value.

[nichhk]

This task ended up being more complicated because many of our date-related components were using local React state instead of the Redux store. So I had to go through these components and remove the local date state, while replacing it with the Redux dates where appropriate.