dockerImageDestination: HasThreadSafePutBlob -> true
dockerImageDestination: HasThreadSafePutBlob -> true

PutBlob() can now be executed concurrently.  Let HasThreadSafePutBlob()
return true to make use of it.

Signed-off-by: Valentin Rothberg <c8d7c67387706f1534261b1aba83f5c355c00ff5@redhat.com>

containers/image,containers/image