binaries packaging and the required R version

The dependencies packaging is done now via `utils::download.packages(.. type='win.binary')`. Due to packaging of the Windows binaries and because these are always fetched in the latest version (cf. #95) the source packages, such as `stringri`, will require the latest R version to be able to build and later run the app. So as a side effect the actually supported min. R version (cf. #94 ) is the latest R version.

On top of that update of R require re-installation of the app (since R path is fixed in the config).