Move engine-api client package

This moves the engine-api client package to `/docker/docker/client`.

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

interface_experimental.go

@@ -0,0 +1,37 @@
+// +build experimental
+
+package client
+
+import (
+	"github.com/docker/docker/api/types"
+	"golang.org/x/net/context"
+)
+
+// APIClient is an interface that clients that talk with a docker server must implement.
+type APIClient interface {
+	CommonAPIClient
+	CheckpointAPIClient
+	PluginAPIClient
+}
+
+// CheckpointAPIClient defines API client methods for the checkpoints
+type CheckpointAPIClient interface {
+	CheckpointCreate(ctx context.Context, container string, options types.CheckpointCreateOptions) error
+	CheckpointDelete(ctx context.Context, container string, checkpointID string) error
+	CheckpointList(ctx context.Context, container string) ([]types.Checkpoint, error)
+}
+
+// PluginAPIClient defines API client methods for the plugins
+type PluginAPIClient interface {
+	PluginList(ctx context.Context) (types.PluginsListResponse, error)
+	PluginRemove(ctx context.Context, name string, options types.PluginRemoveOptions) error
+	PluginEnable(ctx context.Context, name string) error
+	PluginDisable(ctx context.Context, name string) error
+	PluginInstall(ctx context.Context, name string, options types.PluginInstallOptions) error
+	PluginPush(ctx context.Context, name string, registryAuth string) error
+	PluginSet(ctx context.Context, name string, args []string) error
+	PluginInspectWithRaw(ctx context.Context, name string) (*types.Plugin, []byte, error)
+}
+
+// Ensure that Client always implements APIClient.
+var _ APIClient = &Client{}