Merge Delete legacy promotion to Master

This merge does the following
1) Removes product/repo bindings to Environments and Changesets. Replaces it with content views.
2) UI/Api/Model changes to enforce that
3) Removes the  "default content view" binding to a non-library environment. So from now on user cannot directly register a  consumer to an environment. Instead user will have to be specific on the content view. 
4) Migration scripts to enforce this.