* return different error codes for check-version
* Adds data file for exit codes that can be used by ArangoDB applications
* add some exit codes
* better return codes for centos
* add codes in arangod
* remove test code
* prevent re-downloading of starter and other small improvements
* fix some erros
* finish centos
* update urls
* add info about systemd detection
* move further towards a working systemd setup
* set service type to simple
* add arangodb-update-db script
* start work on debian packages
* a db dir that is already in place (former installation) should be reused now
* fix minor bugs
* Implement exit code translation in the windows installer.
* add autogenerated NSIS exit code mapping
Frank Celler
Jan Christoph Uhde
Wilfried Goesgens