Fixes #5719 - make pulp async actions cancellable

The cancelling is done though the task details: running steps tab
fixes #4636 - refactor OperatingsystemExtensions to RedhatExtensions and refactor MediumExtensions
Fixes #5719 - poll directly after sending the cancel
Fixes #6237 - allow canceling remote execution actions
Fixes #6147 - filter both org and env in sys

systems index action does not filter by environment_id when both
organization_id and environment_id are passed; it only filters by
organization_id. This allows the index action to filter by both.
Fixes #6249,BZ1109398: Candlepin proxy routes properly looking up organization.

When the API switched to looking up organization by ID, the Candlepin
proxy routes that required an organization broke since subscription-
manager GUI and CLI pass the organization label and not numerical ID.
Fixes #4172: Prevent alch-edit-select errors by checking if editTrigger exists.
fixes #6204 / BZ 1099016 - Fix gpg key on repo create and yum retrieval

This commit addresses 2 issues:
1. update the repo create to support associating the gpg key url
   in candlepin
2. update the v2 api to expose the 'gpg_key_content' api to enable
   yum clients to retrieve the key
Merge pull request #4244 from dustint-rh/system_index_filter_org_env

Fixes #6147 - filter both org and env in sys
Merge pull request #4263 from bbuckingham/issue-6204

fixes #6204 / BZ 1099016 - Fix gpg key on repo create and yum retrieval
Fixes #6252/BZ1087079 - default to errata_id on bulk errata searches.
Fixes #6258 - env_id & cv_id optional in ak update

Activation Key update should allow passing of environment_id and
content-view to be optional since creation allows the existence
of Activation Keys without a lifecycle-environment or content-view
asociated.
Fixes #6260/BZ1023881 - display OS on content host index page.
Merge pull request #4291 from waldenraines/6252

Fixes #6252/BZ1087079 - default to errata_id on bulk errata searches.
Merge pull request #4290 from dustint-rh/ak_put_env_not_required

Fixes #6258 - make env_id optional in ak update
Merge pull request #4292 from waldenraines/6260

Fixes #6260/BZ1023881 - display OS on content host index page.
Merge pull request #4246 from isratrade/6156

fixes #4636 - refactor OperatingsystemExtensions to RedhatExtensions and refactor MediumExtensions
fixes #6269 / BZ 1110486 - activation key - include description on details pane

Add the description to the 'details' pane to support review/edit.
Merge pull request #4297 from bbuckingham/issue-6269

fixes #6269 / BZ 1110486 - activation key - include description on details pane
Fixes #5503/BZ1102315 - restrict UI interactions to actual permissions.