Legacy promotion removal: Removing changeset code
Changesets: Encapsulating common code

This addresses feedback in #2494 and fixes #2496
Minitest: Regenerated VCR cassettes
Merge pull request #2494 from daviddavis/delete-changeset-promotion

Legacy promotion removal: changeset edition
Migration script for promotion code

This commit implements the following Migration
1)  Create a "Default CVD"  which has all the content  in the library
2) Publish a "Previous Environments View"
3) For each Non Library env -> change the env's default CVV to point to
the "Previous Environments View"
4) Update every system whose cv is null and make em point to "Previous
Environments"
5) Update every Activation Key whose cv is null and point em to
"Previous Environments View"
6) Change the  Org default view's CVE  to point to Default Publish View
(Org default view's will not point to a CVE after this)
7) Update repo create and clone methods to get the default env path
from CVE as  opposed calculating based on env default view or not ....
8) Auto publish on for Library default views
9) Generate metadata for library views