Revert "Add example Scratch project for Experience CS" (#526)

This reverts commit 4d4a123.

The `ProjectImporter` doesn't currently play nicely with the
`default_scope` we've added to `Project`. It correctly created the
experience-cs-example project the first time the `rake
projects:create_all` task ran on the deployment to staging but it fails
on subsequent invocations because the `default_scope` prevents the
importer from finding the existing Scratch project and it therefore
attempts to create it again, resulting in:

> ActiveRecord::RecordInvalid: Validation failed: Identifier has already
been taken (ActiveRecord::RecordInvalid)

Author: chrisroos