Colin/test log

This is a quick hack to store the cpanm logs to a /tmp directory.  There is also some basic command line parsing so that you can do,

perl dist/test_dists --nomirror --lib lib/

If you run it with no command line parameters it should use the original options making it relatively backwards compatible, i.e.

perl dist/test_dists --mirror file:///var/local/CPAN_mirror --lib /tmp/tb2/lib/perl5

It adds a dependency on Path::Tiny and Getopt::Long.