Updating file path location search for config.json

[djengineerllc]

Instead of looking for config.json form current directory when running the program, look for the config.json from the executable running directory. This will allow for calling fail2rest executable from a service w/o getting the "failed to open config: config.json" error.

[Sean-Der]

Looks good to me! Merged with c5a2d036d7004615fca75514d38ed7ab84fd79df

I would also like to add a switch that allows people to specify the path to their config.json, I will make that ticket.