commons_activity_page unnecessarily depends on Panels and Panels IPE

The commons_activity_page module only exports a page manager configuration, which doesn't require either panels or Panels IPE. On our commons site, we don't need/want Panels IPE on the site, so we're not using any of the various commons_*_page node modules (thanks for splitting those out), but the activity streams module is the last holdout with a dependency on Panels IPE.