Pull request 04 04 2013 a

This pull request contains the following:

Create fake investigations, activities, pages, and external activities, and convert tests to user them. PT story https://www.pivotaltracker.com/story/show/44098469

Create fake assignments for the classes and convert tests to use those assignments. PT story https://www.pivotaltracker.com/story/show/44097943

Separate the spec and cucumber database (suggested in PT story https://www.pivotaltracker.com/story/show/44097245).
  - Edit the config/database.yml file to configure cucumber database.
  - Use a different rake task to populate each database => db:test:prepare(rspec) and db:test:prepare_cucumber(cucumber).