add(taskwarrior): pull implementation for new tasks

This implements the pull functionality for new tasks, which are not yet
in the local taskwarrior instance created. WIP for #3.

internal/taskwarrior/task.go

@@ -35,6 +35,14 @@ type Annotation struct {
 	Entry       string `json:"entry,omitempty"`
 }
 
+func (task *Task) AppendComment(description string, time time.Time) {
+	annotation := Annotation{
+		Description: description,
+		Entry:       GoTimeToTaskTime(time),
+	}
+	task.Annotations = append(task.Annotations, annotation)
+}
+
 func NewTask(description string, project string, git_id uint, git_type Type, tags ...string) Task {
 	// TODO: update task struct to include the new user defined value, which shall
 	// also be provided as an argument