Added new task search, scale endpoints.

Now you can scale apps by killing individual tasks.  You can use the
'/v1/apps/$appId/tasks' to list tasks for an app, and then scale
apps by killing individual tasks with a POST to
'/v1/tasks/kill?scale=true&appId=id&host=host&id=taskid'.
Merge pull request #71 from brndnmtthws/scale-by-task

Added new task search, scale endpoints.