Unit tests should work even though slumdown package is not a blog

[djnavarro]

Currently any unit test fails because check_slumdown() correctly throws an error. Tests should perhaps be run in a temporary directory

[djnavarro]

Suggested solution

• refactor so that the slumdown package includes a cached copy of the hugo-slum theme
• installation should use the local copy of the theme not the github repo

Pros:

• ensures that slumdown package and hugo theme are always in sync on users machine
• allows unit tests by installing to a temp directory

Cons:

• bug fixes to slumdown package will force users to update the hugo theme (workaround: maybe allow slumdown updates to cache older versions of hugo-slum and let user call new_slum() with optional versioning argument?)

[djnavarro]

Fixed by including local cache in inst/extdata but having separate functions for remote install and local install of the hugo-slum theme. Unit tests rely on local install to temp directory; additionally there is one test that checks that remote and local produce the same results