Module cleanup

damog,
I've cleaned up the Makefile.PL and sorted a lot of issues that should stop the module from reporting UNKNOWN in the [CPAN testers reports](http://www.cpantesters.org/distro/W/WWW-Tumblr.html#WWW-Tumblr-4.1), and also should address [bug 51526](https://rt.cpan.org/Public/Bug/Display.html?id=51526). In addition to these fixes, it would be very much appreciated if you pushed a new version to CPAN incorporating these fixes.

~ Squeeks