Add container start and supervisor

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

execution/supervisor.go

@@ -0,0 +1,12 @@
+package execution
+
+type Supervisor struct {
+}
+
+type waiter interface {
+	Wait() (uint32, error)
+}
+
+func (s *Supervisor) Add(w waiter) {
+
+}