[Finishes #79484946] Free play links on student dashboard and puzzle headers

Links to the k1 version of Playlab and Artist free play when the user is in a k1 course.

![screen shot 2014-09-29 at 3 25 53 pm](https://cloud.githubusercontent.com/assets/413693/4450618/a12a4684-4827-11e4-83c8-b6cdf1cdc87c.png)

![screen shot 2014-09-29 at 2 37 00 pm](https://cloud.githubusercontent.com/assets/413693/4450623/afceaf36-4827-11e4-961d-3f893315baa3.png)

So I'd start by putting this in ApplicationHelper, so the magic is at least in one place.

Freeplay-ness is a property of the level -- so it does actually happens to be in the properties hash for levels that are created in the levelbuilder. Eg:

````
irb(main):012:0> Script.find_by_name('course1').stages.find_by_position(18).script_levels.find_by_position(10).level.free_play
  Script Load (0.5ms)  SELECT `scripts`.* FROM `scripts` WHERE `scripts`.`name` = 'course1' LIMIT 1
  Stage Load (0.5ms)  SELECT `stages`.* FROM `stages` WHERE `stages`.`script_id` = 33 AND `stages`.`position` = 18 ORDER BY position ASC LIMIT 1
  ScriptLevel Load (0.5ms)  SELECT `script_levels`.* FROM `script_levels` WHERE `script_levels`.`stage_id` = 187 AND `script_levels`.`position` = 10 ORDER BY position ASC LIMIT 1
  Level Load (0.4ms)  SELECT `levels`.* FROM `levels` WHERE `levels`.`id` = 1425 ORDER BY `levels`.`id` ASC LIMIT 1
=> "true"

````

However the playlab ones do not because they are not levelbuilder levels (all that is in the js).