Add support for cross project references for labels
## Summary
Support for cross project references for labels.
## Rationale
1. Cross project label references are currently not supported in GitLab
1. `to_reference` method signature in `Label` model breaks the abstraction introduced in `Referable`.
`concerns/referable.rb: def to_reference(_from_project = nil)`
Signatures:
```
label.rb: def to_reference(format = :id)
commit_range.rb: def to_reference(from_project = nil)
commit.rb: def to_reference(from_project = nil)
external_issue.rb: def to_reference(_from_project = nil)
group.rb: def to_reference(_from_project = nil)
issue.rb: def to_reference(from_project = nil)
merge_request.rb: def to_reference(from_project = nil)
milestone.rb: def to_reference(from_project = nil)
project.rb: def to_reference(_from_project = nil)
snippet.rb: def to_reference(from_project = nil)
user.rb: def to_reference(_from_project = nil)
```
This MR suggests using `def to_reference(from_project = nil, format: :id)` which makes use of keyword arguments and preserves abstract interface.
1. We need support for cross project label references when we want to move issue to another project
It may happen that issue description, system notes or comments contain reference to label and this reference will be invalid after moving issue to another project and will not be displayed correctly unless we have support for cross project references.
Merge request that needs this feature: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/2831
I think that cross project label references may be useful, (example: `Hey, see our issues for CI in GitLab CE! - gitab-org/gitlab-ce~"CI"`).
cc @JobV @DouweM @rspeicher
See merge request !2966
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:
See merge request !2817
