Start work on Container and Process model

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

execution/executor.go

@@ -0,0 +1,17 @@
+package execution
+
+import "io"
+
+type CreateOpts struct {
+	Bundle string
+	Stdin  io.Reader
+	Stdout io.Writer
+	Stderr io.Writer
+}
+
+type Executor interface {
+	Create(id string, o CreateOpts) (*Container, error)
+	List() ([]*Container, error)
+	Load(id string) (*Container, error)
+	Delete(string) error
+}