Merge branch 'dz-root-url' into 'master'

Move user#show and group#show routing under root url

## What does this MR do?

Changes routing so user#show and group#show routing is under root url 

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

no

## Why was this MR needed?

For nice and consistent routing  for user/group show pages:

| before | after| 
|---|---|
| `/u/dzaporozhets` | `/dzaporozhets`| 
| `/dzaporozhets/gitlab-ce` |`/dzaporozhets/gitlab-ce`| 
| `/u/dzaporozhets/snippets` |`/u/dzaporozhets/snippets`| 
| `/groups/gitlab-org`|  `/gitlab-org`| 
| `/gitlab-org/gitlab-ce`|  `/gitlab-org/gitlab-ce`| 
| `/groups/gitlab-org/issues `|  `/groups/gitlab-org/issues `| 

So show page for user and group shown as `/:name` which is much nicer than before. At same time all nested pages like group issues stays under REST `/groups/:name/issues` so we don't need to introduce extra name restrictions ( ex. case when group has project with name "issues")

## Screenshots (if relevant)

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry 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 you do - 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?

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/3620

See merge request !6686

2 files changed, 5 insertions, 10 deletions

diff --git a/app/assets/javascripts/user_tabs.js.es6 b/app/assets/javascripts/user_tabs.js.es6
index 63bce0a6f6f..dfdfa1e7f75 100644
--- a/app/assets/javascripts/user_tabs.js.es6
+++ b/app/assets/javascripts/user_tabs.js.es6
@@ -89,7 +89,7 @@ content on the Users#show page.
       const action = $target.data('action');
       const source = $target.attr('href');
       this.setTab(source, action);
-      return this.setCurrentAction(action);
+      return this.setCurrentAction(source, action);
     }
 
     activateTab(action) {
@@ -142,14 +142,9 @@ content on the Users#show page.
         .toggle(status);
     }
 
-    setCurrentAction(action) {
-      const regExp = new RegExp(`\/(${this.actions.join('|')})(\.html)?\/?$`);
-      let new_state = this._location.pathname;
+    setCurrentAction(source, action) {
+      let new_state = source
       new_state = new_state.replace(/\/+$/, '');
-      new_state = new_state.replace(regExp, '');
-      if (action !== this.defaultAction) {
-        new_state += `/${action}`;
-      }
       new_state += this._location.search + this._location.hash;
       history.replaceState({
         turbolinks: true,
diff --git a/app/assets/javascripts/users_select.js b/app/assets/javascripts/users_select.js
index 05056a73aaf..bcabda3ceb2 100644
--- a/app/assets/javascripts/users_select.js
+++ b/app/assets/javascripts/users_select.js
@@ -71,8 +71,8 @@
               return $collapsedSidebar.html(collapsedAssigneeTemplate(user));
             });
           };
-          collapsedAssigneeTemplate = _.template('<% if( avatar ) { %> <a class="author_link" href="/u/<%- username %>"> <img width="24" class="avatar avatar-inline s24" alt="" src="<%- avatar %>"> </a> <% } else { %> <i class="fa fa-user"></i> <% } %>');
-          assigneeTemplate = _.template('<% if (username) { %> <a class="author_link bold" href="/u/<%- username %>"> <% if( avatar ) { %> <img width="32" class="avatar avatar-inline s32" alt="" src="<%- avatar %>"> <% } %> <span class="author"><%- name %></span> <span class="username"> @<%- username %> </span> </a> <% } else { %> <span class="no-value assign-yourself"> No assignee - <a href="#" class="js-assign-yourself"> assign yourself </a> </span> <% } %>');
+          collapsedAssigneeTemplate = _.template('<% if( avatar ) { %> <a class="author_link" href="/<%- username %>"> <img width="24" class="avatar avatar-inline s24" alt="" src="<%- avatar %>"> </a> <% } else { %> <i class="fa fa-user"></i> <% } %>');
+          assigneeTemplate = _.template('<% if (username) { %> <a class="author_link bold" href="/<%- username %>"> <% if( avatar ) { %> <img width="32" class="avatar avatar-inline s32" alt="" src="<%- avatar %>"> <% } %> <span class="author"><%- name %></span> <span class="username"> @<%- username %> </span> </a> <% } else { %> <span class="no-value assign-yourself"> No assignee - <a href="#" class="js-assign-yourself"> assign yourself </a> </span> <% } %>');
           return $dropdown.glDropdown({
             showMenuAbove: showMenuAbove,
             data: function(term, callback) {