Added dzil build dirs to .gitignore to allow @Git plugin to work properly.

The dirs App-Fetchware-1.000{.tar.gz}? are created by dzil build, and dzil
release obviously also uses them, because before release it obviously does a
dzil build. These dirs are "uncommitted" obviously, and [Git::Check] checks if
there are uncommitted changes, and these dirs very much are. [Git::Check] does
ignore what git ignores, but before this commit, I did not ignore that
directory. Now I do, and now @Git should work great.