generate prerequisites using csv data

[siddhartha-gadgil]

• One should edit the courses.yaml file as well as the separate course files automatically.
• One can read the YAML using moulting-yaml in ammonite by

  import $ivy.`net.jcazevedo::moultingyaml:0.4.0`
  import net.jcazevedo.moultingyaml._
  import net.jcazevedo.moultingyaml.DefaultYamlProtocol._
  import ammonite.ops._
  val txt = read(pwd / "_data" / "courses.yaml").replace("\t", " ")
  val yamlAst = txt.parseYaml
  val data = yamlAst.convertTo[Map[String, Map[String, List[Map[String, String]]]]]

• We modify the inner-most map adding prerequisite fields and then prettyPrint

[siddhartha-gadgil]

done