initial fastlane structure

[IzzySoft]

For your F-Droid inclusion request (also see: #37): issuebot complained about missing Fastlane structures. With this PR I'm sending you what was already set up with my repo. You can simply merge this now, and build on it any time (be welcome to use my Fastlane Cheat Sheet for guidance if needed), e.g. update the description/screenshots, or add per-release changelogs etc. You'll know best what should be there and when 😉

[hagaygo]

Thanks for your pull request.

While i am not sure it will be enough for f-droid , i see no harm in the file additions.

[IzzySoft]

While i am not sure it will be enough for f-droid

Disclosure: I'm one of the maintainers there, so I hope I know what I'm doing 🙈 A question for orientation: do you plan another release soon (as F-Droid usually builds from tags, and Fastlane is not available at the latest tag yet)? If not, for the initial listing we could also specify the commit that added Fastlane. Would that be OK in this case?