use bleach instead of lxml.html.clean for sanitize_html OEE
add autolinking
Fix unicode issue in class_dashboard.
Merge pull request #1475 from edx/dcadams/fix_dashboard_unicode

Do not pull into master: Fix unicode issue in class_dashboard.
Certificates: Add regeneration command

* Adds regenerate_user command, which lets you run certificates for one
  particular user in one particular class, regardless of whether they
  have a pre-existing certificate.