Tweaks to scripts/download_student_forms.py.
Tweaks to scripts/download_student_forms.py.

Handling of the program parameter being empty or invalid is
improved and a list(<generator expression>) is made into a
list comprehension.

These changes come from code review of revision 02b879fb502f.

rhyolight/nupic.son,rhyolight/nupic.son,rhyolight/nupic.son