Add all in one lesson build with Javascript

Make challenges and discussion visibles

This is based on
https://github.com/swcarpentry/instructor-training/pull/437/files and
https://github.com/swcarpentry/instructor-training/pull/439/files,
both write by @ErinBecker.

Updated CONDUCT.md

Rebased of https://github.com/swcarpentry/lesson-example/pull/116/.

Thanks to @tracyteal.

Suggest template language

Add Library Carpentry to the workshop template

make sure that checkpoint version is 0.4.0 or higher

fix swcarpentry/lesson-example#118: use checkpoint::scanForPackages

Includes @drjwbaker's description of Library Carpentry.

Improve wording on syllabus.html

As suggested by @gcapes.

Include

    source: Rmd

in the YAML header.

Revert "ensure dt elements have an id set"

Numbering the lessons in the schedule

Related with https://github.com/swcarpentry/styles/issues/80.

Edit on GitHub

Jekyll doesn't export the _episodes_rmd so we need to flag the files.
Each Rmd file must have in the YAML header

    source: Rmd

https://github.com/swcarpentry/lesson-example/pull/104#issuecomment-283310978

Update copyright year with current year

add a callout about header IDs

Improve round corners on block input and output