Improve command line interface

[davetron5000]

Since my original use for this library isn't straightforward due to the throttling, I think it would still be nice to have a command line interface, something like:

mc ls [list] # shows all tasks or all tasks in list
mc new -l list "name of task" # create a new task, in <list>
mc default_list list_name # make list_name the default list
mc done "name of task" # complete a task
mc done task_id # complete a task
mc rm task_id # delete a task