Added in next and previous hooks for PageBase.
Added in next and previous hooks for PageBase.

danielsamuels/cms,etianen/cms,lewiscollard/cms,dan-gamble/cms,danielsamuels/cms,danielsamuels/cms,lewiscollard/cms,dan-gamble/cms,jamesfoley/cms,dan-gamble/cms,jamesfoley/cms,jamesfoley/cms,jamesfoley/cms,etianen/cms,etianen/cms,lewiscollard/cms