[school-core] Updates

[Justin Riddiough <jriddiough@xxxxxxxxx>]

Per discussions with LM and David recently, I've made some minor
updates to the site this morning.

I have added BSD and Unix to the platform list so that they can be
configured in the software projects.  I haven't added these to the
drop down menu, however.  I will do that when I have a bit more time.

Also renamed the link on the front page from 'Education Software" to
"Educational Software"  The URL path is still education-software
though (only changed the link text)  To change the path across the
site would mean going into the views and updating the .htaccess file
and so is a bit more work.

Added new Software Categories
-Arts
-Language Arts
-Mathematics
-Physical Education & Health
-Sciences
-Social Studies