refs #7706 - extend errata rabl in systems API
Fixes #8384: Remove dependence on ui-alchemy_rails and compass.

With a majority of the UI having been ported to AngularJS and Patternfly
the requirement on ui-alchemy_rails is overhead. This removes the dependence
and re-factors areas that were using resources from alchemy.
Merge pull request #4831 from stbenjam/7706

refs #7706 - extend errata in systems/erratum rabl
Merge pull request #4837 from ehelms/remove-alchemy-2

Fixes #8384: Remove dependence on ui-alchemy_rails and compass.
Fixes #7688: add content hosts tab to the errata details page.

Adds a content host tab to the errata details page that allows
the listing and syncing of applicable content hosts.

http://projects.theforeman.org/issues/7688
Merge pull request #4771 from waldenraines/7688

Fixes #7688: add a content hosts tab to the errata details.
Fixes #8482: add an environment filter to the errata content hosts page.