Add url method to certificate
Return certificate url
Send 422 error instead of 200
update test
Merge pull request #894 from theodi/feature-create-certificates-asynchronously

Create certificates via API asynchronously
Add certification campaign model
Link certificate_generator to campaign
Associate campaign with generator if requested
update libv8 for yosemite
Merge pull request #895 from theodi/feature-track-campaigns

Track campaigns
Add basic admin page
Add switch_user gem
Add swtich_user partial to admin page
Add switch_user config
Merge branch 'master' into staging

Conflicts:
	features/step_definitions/api_steps.rb
Merge branch 'feature-admin-powers' into staging