Remove materials and its assignment

- Remove materials and its assignment.
Refine default data creation task.

- Add logic to create default study materials.
Refine default data creation task.

- Refine logic to create default study materials.
Refine default data yml

- Refine default data yml.
Refine default data creation.

- Refine logic for creation of study materials.
Remove redundant code.

- Remove redundant code.
Merge updates from previous pull request branch

- Merge branch 'pull_request_03_12_2013_a'
  into test_cleanup_03_20_2013_a.
Merge updates from pull request branch

- Merge remote-tracking branch 'pull_request_03_25_2013_a'
  into test_cleanup_03_20_2013_a.
Add column uuid in resource_page table.

- Add column uuid in resource_page table.
Refine default data creation.

- Refine default data creation.
Refine default data creation.

- Add logic to create default assignments.
Add rake task to create default assignments.

- Add rake task to create default assignments for classes.
Create separate cucumber environment.

- Create separate cucumber environment.
Refine yaml data for offering.

- Refine yaml data for offering.
Refine default data yaml.

- Change url for external activity.
Refine default data creation.

- Refine default data creation.
Refine default data creation.

- Refine default data creation.
Change function name to load_common_data.

- Change function name to load_common_data.
Refine default data creation.

- Refine creation of investigations with multiple choice.
Refine default data creation.

- Add data for project in YAML.