Switch Docker package to unpinned from Ubuntu repo

The pinned version in the official docker repo was removed.  Switching
to Ubuntu's package for 16.04 should be stable enough for these
purposes.

Change-Id: I296303d8144149850551677bbe1299dc3a8ef479

deployment_files/global/v1.0dev/software/config/versions.yaml

@@ -434,45 +434,8 @@ data:
         node: quay.io/calico/node:v2.6.5
         settings: quay.io/calico/ctl:v1.6.2
   packages:
-    repositories:
-      - name: docker
-        url: http://apt.dockerproject.org/repo
-        distributions:
-          - ubuntu-xenial
-        components:
-          - main
-        gpgkey: |-
-          -----BEGIN PGP PUBLIC KEY BLOCK-----
-
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-          0C0V9yqtdPdRWVIEhHxyNHATaVYOafTj/EF0lDxLl6zDT6trRV5n9F1VCEh4Aal8
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-          HXITX660jglyshch6CWeiUATqjIAzkEQom/kEnOrvJAtkypRJ59vYQOedZ1sFVEL
-          MXg2UCkD/FwojfnVtjzYaTCeGwFQeqzHmM241iuOmBYPeyTY5veF49aBJA1gEJOQ
-          TvBR8Q==
-          =Fm3p
-          -----END PGP PUBLIC KEY BLOCK-----
     named:
-      docker: docker-engine=1.13.1-0~ubuntu-xenial
+      docker: docker.io
       socat: socat=1.7.3.1-1
     unnamed:
       # nfs-common for the nfs provisioner - dev only.