Add Todos
Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/2425
Tasks:
- Prepare database
- [X] Create a new table (`todos`)
- Tasks Queue view
- [X] Add a number icon showing the number of todos on the top right next to the new and logout button that will redirect the user to the todos page
- [X] Add a chronological list of todos, with the 'Todos' tab active by default
- [X] Add a 'Done' button to each todo
- [x] Add filters (project, author, type, and action)
- Todos generation
- [X] When user issue/mr is assgined to someone
- [x] When user is mentioned on (issues/mr's/comments)
- Mark todo as `done`
- [X] When clicks on the 'Done' button
- [X] When edit issue/mr
- [X] When left/edit a comment
- [X] When reassign issue/mr
- [X] When add/remove labels to issue/mr
- [X] When issue/mr is closed
- [X] When mr is merged
- [X] When added an emoji
- [X] When changed the issue/mr milestone
* Screenshot:
![Screenshot_2016-02-20_12.45.57](/uploads/4b2554b1bde25aed3347e1ae41e8e0c0/Screenshot_2016-02-20_12.45.57.png)
See merge request !2817