Add a 'version' option, so that a version can be specified to 'finddeps'

The ability to specify a version is useful since some software relies on specific versions of cpan modules. If the cpan module is not present for the specified version, an error is thrown as normal; but if it does exist on CPAN, that particular version is pulled instead of the latest to ensure compatibility with the software.
the code style elsewhere is cuddled elses