support longer Summary and Description fields

To match other the char limits for Summary and Description where bumped to 80 and 4000 respectively. The AppDetails view should be checked to work with those longer fields. The longer Description shouldn't require changes, but the longer Summary will. Google Play handles this display pretty well, at least on my device.

here's the change on the server side: https://gitlab.com/fdroid/fdroidserver/merge_requests/55

FWIW, don't forget about applistinfo, the view for each app item on the app lists. In there, summaries over 25-30chars get cut.

Milestone changed to 1.0