Access denied in Joomla 1.6 / CiviCRM 4.0 for backoffice staff wanting to edit or view Personal Campaign Pages that aren't approved yet

1. Backoffice staff need to be able to Edit PCP pages prior to approval. This is currently blocked in Joomla 1.6 (old permission checking code needs to be replaced).

2. The "View PCP" link on the Manage PCPs selector was pointing to the front-end page. This is problematic for "not yet approved" PCP's since the backoffice staff trying to view the page will be redirected to associated contribution page (since in the front-end they don't have permission as anonymous user to view an unapproved PCP). Changed the link title from "View Personal Contribution Page" to "Preview ..." to help clarify that backoffice staff are viewing the page in the back-end and not front-end as constituents will see it.