adding tasks activity in u_milestones

[sbillinge]

We can add todos to milestones tasks from the todo helpers, but it will be convenient to be able to add a list of todos when we create or update a milestone. Add functionality to u_milestones so it can take a list of tasks at the command line and (a) add them to the task list and (b) create them in the todos collection of the right person (in the right database)