Revert "[WFLY-490] / [WFLY-1864] Update the protocol so that servers receiving management requests from a trusted master can request a Subject to use when executing the operation."

This reverts commit af795dbd8155a9f4b063921d67f79f33df62f9c0.
Revert "[WFLY-490] / [WFLY-1853] First make sure the Principals are Serializable so they can be passed from process to process."

This reverts commit d7ba20606a4baa8e59ed79a598dcc0b399570b52.