Deprecate 'docker images --tree' and 'docker images --viz'

* The commands are no longer listed or documented.
* The commands still work but print a deprecation warning.
* The commands should be removed in a future version.

Docker-DCO-1.1-Signed-off-by: Solomon Hykes <solomon@docker.com> (github: shykes)
api/server: replace an integration test with a unit test using engine mocking.

Docker-DCO-1.1-Signed-off-by: Solomon Hykes <solomon@docker.com> (github: shykes)
engine: fix engine.Env.Encode() to stop auto-guessing types.

Docker-DCO-1.1-Signed-off-by: Solomon Hykes <solomon@docker.com> (github: shykes)
api/server: convert TestGetInfo from an integration test to a unit test.

Docker-DCO-1.1-Signed-off-by: Solomon Hykes <solomon@docker.com> (github: shykes)
Merge pull request #5001 from shykes/deprecate-images-viz-tree

Deprecate 'docker images --tree' and 'docker images --viz'
Merge pull request #5004 from shykes/api-unit-tests

Replace integration tests with unit tests for the remote API
remove hack in version

Docker-DCO-1.1-Signed-off-by: Victor Vieux <victor.vieux@docker.com> (github: vieux)
Merge pull request #5006 from vieux/remove_dirty_hack

remove hack in version