Perlbrew Release 0.64

perlbrew 0.64 is released on 2013-06-02T09:44:59+0200

The build directory is removed before a new build.
New command: install-multiple
clean command now also removes tarballs
install command has many extra convienent flags.
Use "http://www.cpan.org" as the default CPAN mirror instead of "http://search.cpan.org/CPAN"
Remove the --insecure / --no-check-certificate command bflags when invoking curl / wget.