Insert pagination utilities from beego/wetalk. Refs #835.
Move pagination to utils/pagination. Refs #837, #835.
Document usage of utils/pagination. Refs #835.
Cleanup pagination documentation. Refs #835.
Remove PaginationController interface and pass context instead. Refs #835.
Merge pull request #837 from bsingr/develop

Insert pagination utilities from beego/wetalk. Refs #835.