author_lesson() now creates lesson.Rmd instead of custom-named lesson
updated DESCRIPTION with Sean's name and incremented version to 2.1
fixed rmd2csv.R so that it works with the new more extensive YAML
added swirl version line to YAML and changed rmd2csv defaults to omnitest
bill's fix for mult_question testing plus a check for comments in corr_ans in rmd2csv
Merge pull request #76 from ncarchedi/master