Add a new "is-task" ps filter

This makes it easier to list containers that are part of a task
(swarm mode) and those who are not.

Signed-off-by: Vincent Demeester <vincent@sbr.pm>
Upstream-commit: 5280ba83e55b94b9d4973a15381e18eb10920233
Component: engine

components/engine/integration-cli/docker_cli_ps_test.go

@@ -136,6 +136,7 @@ func assertContainerList(out string, expected []string) bool {
 	return true
 }
 
+// FIXME(vdemeester) Move this into a unit test in daemon package
 func (s *DockerSuite) TestPsListContainersInvalidFilterName(c *check.C) {
 	out, _, err := dockerCmdWithError("ps", "-f", "invalidFilter=test")
 	c.Assert(err, checker.NotNil)