issue 2353: system groups - enhance to support 'Update All' for packages

While working in issue 2353, found that Katello does not currently
provide a way to request 'Update All' packages for a system group; however,
it does for an individual system.  This commit provides the UI to
support this for a system group.
issue 2353: system/system group - update backend to support 'update all' packages

This commit contains a minor change to allows support for
an 'update all packages' for a system or system group.
This would be the equivalent to an admin executing
a 'yum update' each system.

This capability was available with pulpv1; however, when
we migrated to pulpv2, we missed the modifications to enable
the same functionality.
issue 2353 - regenerating vcr cassettes
Merge pull request #2568 from bbuckingham/issue-2353

Issue 2353: Update All - enable support for Systems and System Groups