This pull request adds a new set of APIs that allows tracking the number of requests performed
by the different registered repositories.
In order to avoid losing data, the repository statistics are archived after the repository is closed for
a configurable retention period `repositories.stats.archive.retention_period`. The API exposes the
statistics for the active repositories as well as the modified/closed repositories.
James Rodewig
Adam Locke
Francisco Fernández Castaño