Enable users to supply a custom template file for more advanced publication layouts.
## Use Case
Some publishers may want a non-standard home page that pulls in multiple streams of posts.
Need T810, so templates can stay simple and focused on showing content, rather than showing content //and// managing posts.
Provide a web-based editor for users to create templates in. They'll define the body of the landing page:
`latestPosts` and `taggedPosts` would be the names of functions included in the final template, which make the corresponding queries (TODO: add task for this)