Changes in move_base_blind:

- Added a new parameter 'max_success_range'. If the goal distance is below this value, the action returns success even if
  movement was blocked by an obstacle.
- New parameter defaults:
  goal_threshold = 0.02
  max_success_range = 0.2

closes #590
In move_base_blind: Renamed max_success_range to goal_threshold_acceptable.