Update c/image to v4.0.1 and buildah to 1.11.3

This requires updating all import paths throughout, and a matching
buildah update to interoperate.

I can't figure out the reason for go.mod tracking
	github.com/containers/image v3.0.2+incompatible // indirect
((go mod graph) lists it as a direct dependency of libpod, but
(go list -json -m all) lists it as an indirect dependency),
but at least looking at the vendor subdirectory, it doesn't seem
to be actually used in the built binaries.

Signed-off-by: Miloslav Trmač <mitr@redhat.com>

vendor/github.com/containers/buildah/changelog.txt

@@ -1,3 +1,29 @@
+- Changelog for v1.11.3 (2019-10-04)
+  * Update c/image to v4.0.1
+  * Bump github.com/spf13/pflag from 1.0.3 to 1.0.5
+  * Fix --build-args handling
+  * Bump github.com/spf13/cobra from 0.0.3 to 0.0.5
+  * Bump github.com/cyphar/filepath-securejoin from 0.2.1 to 0.2.2
+  * Bump github.com/onsi/ginkgo from 1.8.0 to 1.10.1
+  * Bump github.com/fsouza/go-dockerclient from 1.3.0 to 1.4.4
+  * Add support for retrieving context from stdin "-"
+  * Ensure bud remote context cleans up on error
+  * info: add cgroups2
+  * Bump github.com/seccomp/libseccomp-golang from 0.9.0 to 0.9.1
+  * Bump github.com/mattn/go-shellwords from 1.0.5 to 1.0.6
+  * Bump github.com/stretchr/testify from 1.3.0 to 1.4.0
+  * Bump github.com/opencontainers/selinux from 1.2.2 to 1.3.0
+  * Bump github.com/etcd-io/bbolt from 1.3.2 to 1.3.3
+  * Bump github.com/onsi/gomega from 1.5.0 to 1.7.0
+  * update c/storage to v1.13.4
+  * Print build 'STEP' line to stdout, not stderr
+  * Fix travis-ci on forks
+  * Vendor c/storage v1.13.3
+  * Use Containerfile by default
+  * Added tutorial on how to include Buildah as library
+  * util/util: Fix "configuraitno" -> "configuration" log typo
+  * Bump back to v1.12.0-dev
+
 - Changelog for v1.11.2 (2019-09-13)
   * Add some cleanup code
   * Move devices code to unit specific directory.