Simplify configuration

Merged username-removed-124398 requested to merge NicoAlt/fdroid-website:gem-dependencies into master

With https://gitlab.com/fdroid/jekyll-fdroid/merge_requests/10 I was able to simplify the configuration needed for the plugin to work.

The only thing that needs to be added to _config.yml is the list with the two gems jekyll-paginate-v2 and jekyll-include-cache, also if I would like to remove that too: https://gitlab.com/fdroid/jekyll-fdroid/issues/29

CC @pserwylo