When a plans block is first dropped on a page, the javascript is not
loaded and initialised correctly.  This commit makes the following
changes:

- Rewrites the task title links after the callback from getScript
- Sets the block's artefactplugin so the js file is found correctly
- Removes any onclick from task titles before rewriting (in case
  there are two plans blocks on a page)
- Hides the pagination on first load, as the paginator object is not
  present at that point.

Change-Id: I40a04f66b3b8c2818f660c42b898b97cbdedb1f5
Signed-off-by: Richard Mansfield <richard.mansfield@catalyst.net.nz>