Remove redundant pageview segment.io events
MA-135, MA-122 Support CDN and alternative sources with VAL-enabled-videos.
Treat an empty string from the admin form to be None/NULL for the CourseEmailTemplateForm
Merge pull request #5972 from edx/will/remove-page-view-events

Remove redundant pageview segment.io events (ECOM-619)
Merge pull request #5974 from edx/mobile/MA-135-122

MA-135, MA-122 Support CDN, alternative sources with VAL-enabled-videos
Merge pull request #5951 from edx/cdodge/treat-empty-email-template-names-as-NULL

Treat an empty string from the admin form to be None/NULL for the Course...