Allow masters to create projects in groups

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

app/helpers/namespaces_helper.rb

 module NamespacesHelper
   def namespaces_options(selected = :current_user, scope = :default)
-    groups = current_user.owned_groups
+    groups = current_user.owned_groups + current_user.masters_groups
     users = [current_user.namespace]
 
     group_opts = ["Groups", groups.sort_by(&:human_name).map {|g| [g.human_name, g.id]} ]

app/views/groups/_projects.html.haml

 .ui-box
   .title
     Projects (#{projects.count})
-    - if can? current_user, :manage_group, @group
+    - if can? current_user, :create_projects, @group
       %span.pull-right
         = link_to new_project_path(namespace_id: @group.id), class: "btn btn-new" do
           %i.icon-plus

doc/permissions/permissions.md

@@ -40,7 +40,7 @@ If a user is a GitLab administrator they receive all permissions.
 |------|-----|--------|---------|------|-----|
 |Browse group|✓|✓|✓|✓|✓|
 |Edit group|||||✓|
-|Create project in group|||||✓|
+|Create project in group||||✓|✓|
 |Manage group members|||||✓|
 |Remove group|||||✓|