Two issues:
1. The constraints in the resources were incorrect. Here's what it was before:
```
group_milestone GET /groups/:group_id/milestones/:id(.:format) groups/milestones#show {:id=>/[a-zA-Z.0-9_\-]+(?<!\.atom)/, :group_id=>/[a-zA-Z.0-9_\-]+(?<!\.atom)/}
```
In this case, id is actually the title of the milestone, which can be anything at the moment.
After:
```
group_milestone GET /groups/:group_id/milestones/:id(.:format) groups/milestones#show {:id=>/[^\/]+/, :group_id=>/[a-zA-Z.0-9_\-]+(?<!\.atom)/}
```
2. `parameterize` would strip all Unicode characters, leaving a blank string. Rails would report something like:
ActionView::Template::Error (No route matches {:action=>"show", :controller=>"groups/milestones", :group_id=>#<Group id: 48, name: "ops-dev", path: "ops-dev", owner_id: nil, created_at: "2015-11-15 08:55:30", updated_at: "2015-12-02 06:23:26", type: "Group", description: "", avatar: "sha1.c71e73d51af1865c1bbbf6208e10044d46c9bb93.png", public: false>, :id=>"", :title=>"肯定不是中文的问题"} missing required keys: [:id]):
This change uses the babosa library to create a better slug, which surprisingly
isn't actually used by the global milestone controllers. Instead, they use the
title passed as a query string for some reason.
Closes https://github.com/gitlabhq/gitlabhq/issues/9881
Fix constraints
Previously this controller would in multiple places load tons (read:
around 65000) project and/or group IDs into memory. These changes in
combination with the previous commits significantly cut down loading
times of user profile pages and the Atom feeds of users.
refactor login as to be impersonation with better login/logout
Modifies the existing "login as" feature to be called impersonation.
This also adds:
* Application keep track of who is impersonating the user so they can revert back to the original user without having to log out.
* Stores the user profile via `HTTP_REFERER` so you get redirected back to the person you have impersonated once you stop.
## Screenshots:


See merge request !1702
Modifies the existing "login as" feature to be called impersonation, as
well as keeping track of who is impersonating to revert back to that
user without having to log out.
Safari 9.0 does not yet honor the HTML5 `origin-when-cross-origin` mode,
and it's possible load balancers/proxies strip the HTTP_REFERER from
the request header. In these cases, default to some default path.
Closes#3122
Closes https://github.com/gitlabhq/gitlabhq/issues/9731
Add ability to remove the fork relationship from project settings


Replaces !1579.
Fixes#2578.
See merge request !1636
This was previously possible through the API but can now be done
through the project#edit settings screen if the current user is
the owner of the project.
Update changelog
Cleanup CI pages
- [x] Remove `ci/projects/:id` page
- [x] Remove Continuous integration from project menu
- [x] Remove unused css/js
- [x] Remove Ci::Commit and Ci::Build controllers
- [x] Move CI services to project settings area
cc @ayufan
Part of #2594
See merge request !1529