Add v2 server config support with plugin URIs

Closes #3210

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>

daemon_config_linux_test.go

@@ -127,6 +127,7 @@ func TestDaemonRuntimeRoot(t *testing.T) {
 		}
 	}()
 	configTOML := `
+version = 1
 [plugins]
  [plugins.cri]
    stream_server_port = "0"
@@ -221,6 +222,7 @@ func TestDaemonCustomCgroup(t *testing.T) {
 
 	customCgroup := fmt.Sprintf("%d", time.Now().Nanosecond())
 	configTOML := `
+version = 1
 [cgroup]
   path = "` + customCgroup + `"`