Document that Dancer2 should be fatpackable

[veryrusty]

Several issues and Pr's (e.g. #432 #437 #485) note the desire/assumption that Dancer2 should be fatpackable, though this is not mentioned anywhere in the source or docs.

It looks like the latest releases of MIME::Types (v2.0+) may not by fatpackable as the mime types db was moved to a separate file.

[xsawyerx]

This seems like two issues:

• Document Dancer2 should be fatpackable.
• Is MIME::Types 2.0+ fatpackable?

Let me fix the first one and we'll open a new issue for the second.

[xsawyerx]

Fixed by 11d3e3c.

Thanks. :)