Content views: Removing more unused files

Removing content view version controller/view files and content view refresh
code.
use the yum_clone distributor during CV publish

if a repository has no filters applied, then we can just use
the yum_clone distributor for metadata generation and save a few minutes
Merge pull request #3632 from jlsherrill/cv-rework-clone

use the yum_clone distributor during CV publish
Merge pull request #3653 from daviddavis/more-cv-removal

Content Views: Removing version UI and refresh code
API V2: Built out content views and added tests