Fixed download links for ruby 1.9+

Ruby 1.9 removed the .each method from a string.
I replaced by splitting on newline first.
Merge pull request #41 from binford2k/tickets/31/fix_download_links_each_to_split

Fixed download links for ruby 1.9+
Initial support for .instructor tag

This allows the use of the instructor tag.

This will only display the contents of that tag when localhost prints
the /onepage handler. For the time being, it simply suppresses the
output completely. My next revision, when I get time for it, will be to
add new endpoints so that we can print both an instructor guide and a
solutions manual. This will allow authors to use the tag without
buggering up their output though.

Expect the new endpoints in the next few weeks, but I need to get
Extending and the LMS up and running first.
Merge pull request #42 from binford2k/add_instructor_guide_tag

Initial support for .instructor tag