Fix progress complexity
Fix duplicate code
Make mandatory_completed less complex
Don't override search method
Add certificate.status method
Use presenters for usage data
Refactor counts

Conflicts:
	test/unit/certificate_test.rb
Refactor set_expired
Remove unused code
Whoops
Refactor get_responses
Shall we use concerns?
Add concerns for counts
Autoload concerns
Mix in class methods
Merge pull request #797 from theodi/feature-improve-certificate-model-code-quality

Improve certificate model code quality