Query limits should be properly implemented

[tunix]

Currently we use limits after the SQL query execution. We need to do this during SQL query execution. And we need pagination together with limiting.

For example; assuming that I pass &limit=10&next=123 as query parameters, I should be able to get next 10 records after record with id 123. Therefore we need to change the queries as well to include record ids (can be user id, commit id, project id etc..)