MakeMaker's NAME must be a valid package name, not ditribution name replacing - with ::

`$self->zilla->name` contains distribution name and it might be different from "main_module" package names, which is required by MakeMaker's NAME.

From perldoc ExtUtils::MakeMaker:

    "NAME" must be a valid Perl package name and it must have an
    associated ".pm" file. For example, "Foo::Bar" is a valid "NAME" and
    there must exist Foo/Bar.pm.

cc @xdg