Release 0.48

Perlbrew Release 0.48

perlbrew 0.48 is released on August 24 2012 with these changes

• The build log output "build.log" is now named after the installation name for eaiser reference.
• Fix the invokation configure command to actually contains -Duserelocatableinc
• Experimental: bash/zsh users may put this to shell init instead: eval "$(~/perl5/perlbrew/bin/perlbrew init -)"
• A few output message updates