Add task.ID() API

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

process.go

@@ -30,6 +30,8 @@ import (
 
 // Process represents a system process
 type Process interface {
+	// ID of the process
+	ID() string
 	// Pid is the system specific process id
 	Pid() uint32
 	// Start starts the process executing the user's defined binary

task.go

@@ -169,6 +169,11 @@ type task struct {
 	pid uint32
 }
 
+// ID of the task
+func (t *task) ID() string {
+	return t.id
+}
+
 // Pid returns the pid or process id for the task
 func (t *task) Pid() uint32 {
 	return t.pid