Configure db after package installation

The ponyexpress db should be created directly after package installation.

Signed-off-by: Christoph Kassen <c.kassen@telekom.de>
Load configuration from file

Load configuration from /etc/pony-express/ponyexpress.cfg, Fail silently
when the file is not available.

Default to production configuration

Signed-off-by: Christoph Kassen <c.kassen@telekom.de>