Topic/no smartmatch

Any dzil operation in 5.18 or 5.19 starts off with this warning:

    Smartmatch is experimental at /Users/ether/.perlbrew/libs/19.0@std/lib/perl5/Dist/Zilla/App/Command/podpreview.pm line 50.


This PR removes the use of smartmatch, and fixes a typo I spotted while in the file :)