Create output directories for generated datatypes

[stephen-soltesz]

The traceroute-caller service should create output directories on startup so archiving processes like pusher or jostler have access to these directories. If traceroute-caller creates the directory it should guarantee that it has write permission and the archiving processes can start minimal races.

This functionality is preferred to externally managing the creation of these directories or waiting until traceroute-caller runs its first trace and writes the output. The timing of this is not always guaranteed.