fixes #5151 - system actions: dynflow several more actions

This commit converts the following system actions to use dynflow:
- errata install
- package update, update-all
- package group install, remove
Merge pull request #3970 from bbuckingham/system-actions

fixes #5151 - system actions: dynflow several more actions
fixes #5183 - Rename Systems to Content Hosts throughout the UI
fixes #5183 - renaming files to support the system to content-host change
fixes #5183 - fixing bugs
fixes #5183 - tests: update angular js tests for system -> content host name change
fixes #5183 - system -> content host rename on the content dashboard

This does not address renaming 'system groups' as there will be a separate
effort to rename those to 'host collections'.
fixes #5183 - fixes post master rebase
fixes #5183 - fix after master rebase