Run a one-time conversion background process:

1. Convert the existing offline data containing /mobile-sections-lead and /mobile-sections-remaining responses to mobile-html
2. Change offline interceptor logic to look for mobile-html jsons in the 'converted files' cache instead of its internal 'okhttp-cache'
3. Add logic to fall-back to the image resolution we have, when offline, instead of the actual resolution requested
4. Bundle css files for sometime for offline usage
5. Create /page/summary responses from existing jsons, and store it in a cache for offline use
6. Add more logic to detect if the okhttp has since cached a more complete response for /mobile-html, or /page/summary which will happen if the user opens the saved page while online. Then we need to delete the 'converted' file for the article

Steps for QA

1. Install an older version of app.
2. Save a few pages for offline reading
3. Go offline and make sure they are stored correctly. Go back online.
4. Install the mobile-html version
5. Go offline after the installation is complete
6. Should be able to read the saved articles without any issues

Please try with a couple different older versions, skip a version or two.