Revert "Customized the entity file for CSC151 2013F."

This reverts commit d659f23a358ad6efbc5186fc98cd6dd56fd3e172.

That commit was not supposed to be in the generic branch.
Add standard disability policy page.
Add link to disabilities page.
Add dummy file in the examples directory so that the directory is
in the repo.
Add sample Racket file.
Update .gitignore to ignore some of the linked xsl files.
Merge branch 'master' of https://github.com/rebelsky/courses