Provide gitignore file for the configuration server's working directory

[mariusoe]

Currently, the configuration server's working directory contain files which will not be committed, e.g. the "users.db" file. When showing the working directories Git status, these files will always appear as new files.

In order to solve this problem, the configuration server can provide a ".gitignore" file for its working directory, which excludes these specific files from the working directory's local Git repository.