Clarify disable/delete in sensu-cli

[asachs01]

When disabling/deleting a user, the verbiage used in the cli tool seems unclear to me. IMO there's a difference between disabling and deleting a user. Disabling would imply that the user's account is disabled, but the account still exists. Deleting would imply that the account is removed entirely.

Expected Behavior

Sensu cli has a "delete" verb.

Current Behavior

Sensu cli currently has "disable" as a verb, which actually deletes the user resource:

Possible Solution

Change the verb to delete

[asachs01]

Just noticed #2540 thanks to @apaskulin