Repo cleanup, directly usable after cloning/ unpacking the zip

Fixes https://github.com/mboinet/ttrss-mobile/issues/67.

Once this is merged you could, for example, `git tag 1.0-1` and use Github's release feature (https://github.com/blog/1547-release-your-software, https://help.github.com/articles/creating-releases) to help having a proper releases pages (as requested in https://github.com/mboinet/ttrss-mobile/issues/42).

This would be better than storing binary files in the git repository.