Fixes #6055 - HC add/remove-content-host take uuid

the host-collection command's --system-id option was accepting database
ids instead of uuids. This uses the
add_host_collections/remove_host_collections action instead of the
AssociatingCommands (which uses the update action). This is a simpler
approach than trying to alter/override the behavior of an
AssociatingCommand to accept uuids.
Fixes #6071 - override CH --id desc

content-host's helpful message for --id in the create/update/tasks/info
command should ask for IDS not UUIDS.
Fixes #6096 - override sub --system-id description

hammer subscription list/delete-manifest --system-id flag's description
describes uuid when it should just describe ID
Fixes #6056 - HC override desc create/update sysid

Override host-collection create/update's description for --system-ids so
that it asks the user for ids.
Merge pull request #180 from dustint-rh/hc_rm_associating_commands

Fixes #6055 - HC add/remove-content-host take uuid
Merge pull request #181 from dustint-rh/override_hc_system_ids_desc

Fixes #6056 - HC override desc create/update sysid
Merge pull request #183 from dustint-rh/override_ch_id_desc

Fixes #6071 - override CH --id desc
Merge pull request #185 from dustint-rh/override_subs_sys_id_desc

Fixes #6096 - override sub --system-id description