226 rake scrape tutorials (#241)

* abstract class for handling imports from various tutorial repos #226

* switched javascript tutorial scrape to use abstract job #226

* added new tasks for handling other language tutorials #226

* expanded documentation on new tutorial scrape jobs #226

* removed right-code #226, #224

* removed right-code (and doc-content, left-doc) #224

* now using public repo #226

* no right-code layout

* position