* replace page.root with 'base' variable that knows path level

* deal with case of trailing / in URL

* use link to figure out path for logos

* simplify path building for favicons

* baseurl isn't used in our template so it can removed
* use 'base' variable for path root instead of unecessary http request to
  site.url

* replace page.root with 'base' variable that knows path level

* deal with case of trailing / in URL

* use link to figure out path for logos

* simplify path building for favicons

* baseurl isn't used in our template so it can removed
* use 'base' variable for path root instead of unecessary http request to
  site.url

* rename variable, consolidate comments

* rename variable in template files

See https://help.github.com/articles/about-community-profiles-for-public-repositories/.

This is based on https://github.com/swcarpentry/lesson-example/pull/127/.

by run

~~~
$ find _includes -type f -exec sed -i "s/page.carpentry/site.carpentry/g" {} \;
$ find _layouts -type f -exec sed -i "s/page.carpentry/site.carpentry/g" {} \;
$ find _extras -type f -exec sed -i "s/page.carpentry/site.carpentry/g" {} \;
$ find _episodes -type f -exec sed -i "s/page.carpentry/site.carpentry/g" {} \;
$ find bin -type f -exec sed -i "s/page.carpentry/site.carpentry/g" {} \;
$ find assets -type f -exec sed -i "s/page.carpentry/site.carpentry/g" {} \;
~~~

Includes @drjwbaker's description of Library Carpentry.

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

Add label to search box and navigation arrows.

1.  Use site.root for root path if set, otherwise use site.github.url.
2.  Display extra files for workshop-template repo as well as for lessons.