Add group filtering by name for API

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

doc/api/groups.md

@@ -19,6 +19,8 @@ GET /groups
 ]
 ```
+You can search for groups by name or path with: `/groups?search=Rails`
+
 ## Details of a group
 Get all details of a group.

lib/api/groups.rb

@@ -25,11 +25,14 @@ module API
       # Example Request:
       #  GET /groups
       get do
-        if current_user.admin
-          @groups = paginate Group
-        else
-          @groups = paginate current_user.groups
-        end
+        @groups = if current_user.admin
+                    Group.all
+                  else
+                    current_user.groups
+                  end
+
+        @groups = @groups.search(params[:search]) if params[:search].present?
+        @groups = paginate @groups
         present @groups, with: Entities::Group
       end