Reload configuration without restart

[acharal]

Current configuration lies in /etc/semagrow/repository.ttl and /etc/semagrow/metadata.ttl
If configuration changed in these files semagrow needs to be restarted in order to apply the changes.
However, it is useful to provide the functionality to hot reconfigure without restarting.
Moreover a useful extension is to provide an API for configuration.

A potential use-case would be to deploy semagrow using Kubernetes and configure semagrow through a operator using CDR.