Add default config source to Config class
Add default config source to Config class

fabpot/composer,localheinz/composer,milleruk/composer,gencer/composer,vdm-io/composer,alcohol/composer,johnstevenson/composer,nicolas-grekas/composer,dzuelke/composer,naderman/composer,pierredup/composer,stof/composer,staabm/composer,andrerom/composer,erasys/composer,composer/composer,stefangr/composer,SpacePossum/composer,slbmeh/composer,floverdevel/composer