added WaitingList ref to task.rb, rearranged code and rdoc for better readability
Fixed syntax error in migration, committing new schema
Added factory and sanity-check spec for WaitingRoom
Basic specs for adding a task to waiting room and making sure no
duplicate tasks in waiting room
moved developer-facing README into doc/README_FOR_APP.md and made the toplevel README.md researcher-facing.  From now on please add developer-specific info to doc/README_FOR_APP.md.
Added preferred & minimum group size to Condition, including
validations, specs, and changes to scaffolded
views/conditions/_form.html.erb partial.
Changed Condition factory to specify group sizes, since required for validity.