working pagination for category items
Merging category index page
added invitee model and controller. users can now invite their friends via email to create new invitees
Merge branch 'master' of https://github.com/dancingshell/Wefridgerator
merge
working action mailer. users can now input invite emails to invite others to join their group
fixed bug that shows all categories before slice tehm for pagination. added security so that users cannot see groups if they are not a member
User can now comment on the categories index page and stylized categories index page