In demo_image_repo, unload old keys & publish metadata on revoke
In demo_image_repo, unload old keys & publish metadata on revoke

In revoke_compromised_keys, unload the old keys in addition to
just loading the new keys. Also actually move written metadata
to the live hosted directory when revoke occurs (in addition
to just writing the metadata to metadata.staged)

awwad/uptane,uptane/uptane,shikhar394/uptane,shikhar394/uptane,uptane/uptane,awwad/uptane