add a method to decide the the location of config file, for that is relative to PERLBREW_ROOT.
add a method to decide the the location of config file, for that is relative to PERLBREW_ROOT.

ptolemarch/App-perlbrew,ptolemarch/App-perlbrew,calid/App-perlbrew,josl/App-perlbrew,ptolemarch/App-perlbrew,josl/App-perlbrew,Asuza/App-perlbrew,dagolden/App-perlbrew,josl/App-perlbrew,rafl/App-perlbrew,rafl/App-perlbrew,rafl/App-perlbrew,Asuza/App-perlbrew,Asuza/App-perlbrew,calid/App-perlbrew,dagolden/App-perlbrew