Move templates into DuckPAN

[GuiltyDolphin]

The original purpose of #335 was to improve the existing templating system - one of these changes was to move templates into DuckPAN.

What are the benefits / Why?

• The only thing that actually uses templates (AFAICS) is DuckPAN - so there isn't a huge point to keeping them separate.
• Because DuckPAN makes heavy use of templates, it is easier to update any template systems if the templates reside within DuckPAN as auxiliary files.
• Having templates within a single repo also makes it easier to mass-update them if required.
• We can also make better use of Text::Xslate's features, such as cascading and inclusion as we may keep additional template files around that aren't directly related to any one repository.
• Like above, we can easily pull out shared features of the templates into files accessible by all the templates.
• There are some bugs with existing templates, such as cheat sheet names (using underscores rather than '-' aka the ID).

/cc @zachthompson @moollaza

[GuiltyDolphin]

@zachthompson @moollaza Have you any thoughts on this?

We already contain various information about the repos in DuckPAN, so if anything this would only improve (in a good way) the coupling of the system.

It would also make it easier to move the templates out into another system (say, metadata) if desirable in the future (changes only need to be made in one place).