Make Dancer2 PAR Packable

[webmind]

At the moment Dancer2 is not packable with PAR. While it is Fatpackable, this leaves out the option of having packs which rely on XS bindings such as with packages as Crypt::NaCl::Sodium

[cromedome]

@webmind I can see how this would be helpful, but we don't have time to take this one on for now. If you can get a PR that gets us most of the way there, even if it needs some work/revision, it would help accelerate the development/inclusion of this.

Thanks!