add users API

lib/api.rb

@@ -1,2 +1,31 @@
-class Gitlab::API < Grape::API
+require 'api/entities'
+require 'api/helpers'
+
+module Gitlab
+  class API < Grape::API
+    format :json
+    helpers APIHelpers
+
+    resource :users do
+      before { authenticate! }
+
+      # GET /users
+      get do
+        @users = User.all
+        present @users, :with => Entities::User
+      end
+
+      # GET /users/:id
+      get ":id" do
+        @user = User.find(params[:id])
+        present @user, :with => Entities::User
+      end
+    end
+
+    # GET /user
+    get "/user" do
+      authenticate!
+      present @current_user, :with => Entities::User
+    end
+  end
 end