Initial linex4red-archive-keyring

Initial linex4red-archive-keyring

Partly based on debian-keyring, but using Makefile optimizing and
still handling the public keys manually and storing them in armored
format and dearmor them before packaging.

- Add Makefile with sub-directories to collect GPG keys in armored or
  binary format and convert them into binary keyring format.
- Add all files for debianization
- Add README and example source list files
- Add .gitignore to ignore all files, which are created during processing
  the Makefile and building the Debian package
- Add debian/sources/options to omit packaging the .git and .gitignore
  files from the native source package. Because of a bug in dpkg-source
  this would requires a newer dpkg-dev package version and related
  debhelper version as supported by Debian Jessie-Backports.
  But requesting a newer debhelper version would omit re-building the
  linex4red-archive-keyring from the Debian source packages on those old
  systems.
- Add peter.henn@web.de public key
- Add debian@linex4red.de as repository public key