People in Space - Fix broken API call and country flag icon.

**What did I fix?**

* The IA was using an API file that was broken. I changed the file to a working one and I can confirm it now works as expected.

* I also noticed the country flags didn't work for some of the astronauts. By looking through the API JSON file, I noticed that some of the countries started with an uppercase letter. Our check in JavaScript only checks for the lowercase version. I simply changed it to transform the API country to lowercase. The country flags now work fine.