Resolve "Implement config file so we can have a nice systemd service with default config file"

Closes #27 (closed) Closes #26 (closed)

Still todo:

• Install the service file after installation and start it after installing (postinst)
• Stop the service and remove the service file before uninstalling (prerm)
• Create the directories: /etc/ocspd/ and /var/log/ocsdp/
• ocspd.core.excepthandler now uses a hardcoded path global variabl, not going to fix