Fixed typo in the method 'perpage_key', dbbame changed to dbname

This typo was introduced by PR #562 and was causing a crash while
changing the page setting on a view with paging.
Merge pull request #621 from AparnaKarve/fix_typo_dbbame_to_dbname

Fixed typo in the method 'perpage_key', dbbame changed to dbname