Revert "allow overwrite in untar"

This reverts commit 5a3d774e5651da772a065282a1fb1a31e19e911c.

Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@docker.com> (github: crosbymichael)
Revert "improve untar when using files instead of directories. Specifies behavior on non-existant targets."

This reverts commit 1c8d3106df0bd2aba304c7b3863949ca11c2b133.

Conflicts:
	archive/archive_test.go

Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@docker.com> (github: crosbymichael)
Tests for ADD tar

Docker-DCO-1.1-Signed-off-by: Tibor Vass <teabee89@gmail.com> (github: tiborvass)
Merge pull request #26 from tiborvass/fix-add-tar-test

Tests for ADD tar
Merge pull request #6911 from crosbymichael/revert-archive

Revert archive changes around creating