Addition: Statistics methods to the Page Model

Adds Page->getTotalPageViews($date = null) &
Page->getPageStatistics($limit = 20) statistic methods to the Page
model, there is no way to 'legally' get this data for Pages at the
moment, where as the is for Files via the File->getDownloadStatistics()
& File->getTotalDownloads().
Merge pull request #791 from olsgreen/page-total-views

Addition: Statistics methods to the Page Model