copy missing `clafer.css` file re: http://gsd.uwaterloo.ca:8888/question/634/wiki-installation-procedure
copy missing `clafer.css` file re: http://gsd.uwaterloo.ca:8888/question/634/wiki-installation-procedure

The wiki should always check and recreate the `clafer.css` file if
missing.

gsdlab/claferwiki,gsdlab/claferwiki