* 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

Close carpentries/styles#325

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

Close swcarpentry/lesson-example/193

https://cran.r-project.org/doc/manuals/r-patched/R-exts.html#Specifying-URLs

Close #211

Close #217

Close #150

Close https://github.com/swcarpentry/lesson-example/issues/145.

Close #178