Add type_of_error and next_steps columns to concept_progresses table.
Merge branch 'master' into concept-columns
Make student unit view match mockup.
Improve user experience when interacting with concepts.
Update specs to reflect UI changes for concept interaction.
Remove comments.
Merge pull request #87 from graspapp/remove-comments

Remove comments.
Make concept detail view match mockup.
Add user interface for type of error and next steps.
Merge pull request #90 from graspapp/concept-columns

Integrate breakthrough updates into application.