Introducing versioning of configuration files in config-server

[mariusoe]

Currently, all configuration files are located in the working directory and will be overwritten if its content is changed using the configuration server's endpoints. This means that in case of a wrong change, the previous content is lost.

In order to prevent data loss and prevent unwanted file changes, the abbility of versioning should be introduced.

In this ticket, a mechanism should be introduced which does a version of the configuration files, thus, each change is logged and can be restored if necessary. The configuration server should always use/deliver/provide the latest file version. Furthermore, any change should trigger a new file version. (In future ticket, creating a new version of a file can be triggered manually and a "dirty" state will exist)