TS-3002: Add DSCP support to header_rewrite
Revert "TS-2999: Add dscp_remap plugin to build and update CHANGES and NOTICE"

This reverts commit 04699c5f7a2b22eaf987e58ceb1b0d89c22c06b6.

Conflicts:
	CHANGES
Revert "TS-2999: Add dscp_remap plugin code"

This reverts commit 279402a5522ad2b94186bd35c516e17c0d0491f4.