Update README.md
fix bug in count_units
check for empty line at end of lesson
check if there is something to test before running testit()
prepare for new script question type
Merge pull request #8 from swirldev/script

prepare for new script question type
update text in initLesson.R and customTests.R
change new_yaml to new_lesson, update docs, deprecate author_lesson, etc
a few more tweaks for the version increment to 0.3
add_to_manifest() and get_lesson() added
update hlp()
check for newline at end of manifest before appending with add_to_manifest()
add error handling for more helpful feedback when using testit()
some much needed updates to swirl2html -- now handles script type questions
add course2html for batch processing of swirl2html
add find_units()