Properly remove the "Edit Page" WP adminbar menu when on a BP page.

'bp_init' is too early to run this as the WP adminbar sets up on
'template_redirect', which runs later.

Instead of 'bp_init', we run our adminbar overrides on
'add_admin_bar_menus', which is a more, appropriate hook to use.

git-svn-id: https://buddypress.svn.wordpress.org/trunk@7859 cdf35c40-ae34-48e0-9cc9-0c9da1808c22