Improve error message when configuration file does not exist.
Improve error message when configuration file does not exist.

tejerka/atoum,GuillaumeDievart/atoum,jubianchi/atoum,CedCannes/atoum,gpaton/atoum,GuillaumeDievart/atoum,gpaton/atoum,jubianchi/atoum,mageekguy/atoum,CedCannes/atoum,vonglasow/atoum,mageekguy/atoum,mikaelrandy/atoum,agallou/atoum,tejerka/atoum,mikaelrandy/atoum,Tiross/atoum,Tiross/atoum,vonglasow/atoum,agallou/atoum