Add task-get-parameters command

 * Task parameters can be a huge size and getting
   them should be the separate command.
   Otherwise table task-list become unreadable.
 * Unit tests on task-get-result and task-get-output

Change-Id: If86a69d24786f73d3b3c297d0b8288336a1a5433
Merge "Add task-get-parameters command"