Merge branch 'dz-remove-namespaces-path-uniq' into 'master'

Modify namespace name and path validation

## What does this MR do?

* Allow same namespace name with different parent_id
* Allow same namespace path. Uniq validation should be handled by routes table

## Are there points in the code the reviewer needs to double check?

migrations

## Why was this MR needed?

So we can use same name in different nesting like: 

```
gitlab-ce/foo
gitlab-com/foo
foo/gitlab-ce
```

## Screenshots (if relevant)

no

## Does this MR meet the acceptance criteria?

- ~~[Changelog entry](https://docs.gitlab.com/ce/development/changelog.html) added~~
- ~~[Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)~~
- ~~API support added~~
- Tests
  - [x] Added for this feature/bug
  - [x] All builds are passing
- [x] Conform by the [merge request performance guides](http://docs.gitlab.com/ce/development/merge_request_performance_guidelines.html)
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if it does - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

## What are the relevant issue numbers?

https://gitlab.com/gitlab-org/gitlab-ce/issues/2772

See merge request !8013

1 files changed, 1 insertions, 2 deletions

diff --git a/app/models/namespace.rb b/app/models/namespace.rb
index 37374044551..f0479d94986 100644
--- a/app/models/namespace.rb
+++ b/app/models/namespace.rb
@@ -17,14 +17,13 @@ class Namespace < ActiveRecord::Base
   validates :owner, presence: true, unless: ->(n) { n.type == "Group" }
   validates :name,
     presence: true,
-    uniqueness: true,
+    uniqueness: { scope: :parent_id },
     length: { maximum: 255 },
     namespace_name: true
 
   validates :description, length: { maximum: 255 }
   validates :path,
     presence: true,
-    uniqueness: { case_sensitive: false },
     length: { maximum: 255 },
     namespace: true