restful: Add pagination support

restful: Add pagination support

This commit adds a pagination support via paginate decorator. The
decorator will paginate the output if it is told to. The first page is
0, the last page is -1. The decorator was applied to /request endpoint
so you can get requests in hunderds if you supply the endpoint with
?page=N. If no ?page=N is supplied, the decorator will output the full
list.

Signed-off-by: Boris Ranto <branto@redhat.com>