added a mechanism to change the default logger implementation
Created originally on Bitbucket by sdorra (Sebastian Sdorra)
Was already merged in Bitbucket before import, marked as merged by the import user
LoggerFactory tries to load a implementation of LoggerFactory from META-INF/services/com.aragost.javahg.log.LoggerFactory with the ServiceLoader. If not implementation can be found, it uses the default java.util.logging implementation.