Challenge Listings: "Points" should be "Purse"

Challenge Listings: Past contests bucket - "Points" should be "Purse" https://test-community-app.topcoder-dev.com/challenges?bucket=past https://test-community-app.topcoder-dev.com/challenges? user: dan_developer/appirio123

<img width="1440" alt="Screenshot 2020-05-25 at 11 59 29 AM" src="https://user-images.githubusercontent.com/58783823/82785029-6cb41d80-9e7f-11ea-8aa2-e78cffa18e44.png">

Final Submission Guidelines

Git issue link: https://github.com/topcoder-platform/community-app/issues/4405