PostService - skipError on 400, deduplicate
PostService - skipError on 400, deduplicate

go to Services > Catalogs, Catalog Items accordion
create a new Catalog Item, of type Ansible Playbook
do stuff to trigger a validation error on saving (duplicate name, badly configured embedded ansible)

Before - you'll see the error modal pop up, and a flash message.

Now - you'll only see the flash message.

This also cleans up postService:
  * there were 2 identical brances differing in `action: 'edit'` vs `action: 'create'`
  * handleSuccess handled errors, separately from handleFailure but same way
  * $timeout was being used to compensate for not having originally injected the angular API variant

(`postService` is only used by that single form - but that's a TODO for later)

https://bugzilla.redhat.com/show_bug.cgi?id=1509809

ManageIQ/manageiq-ui-classic,ManageIQ/manageiq-ui-classic,ManageIQ/manageiq-ui-classic,ManageIQ/manageiq-ui-classic