Authenticate non-API requests with personal access tokens.

- Rename the `authenticate_user_from_token!` filter to
  `authenticate_user_from_private_token!`
- Add a new `authenticate_user_from_personal_access_token!` filter
- Add tests for both.

spec/controllers/application_controller_spec.rb

@@ -30,4 +30,70 @@ describe ApplicationController do
       controller.send(:check_password_expiration)
     end
   end
+
+  describe "#authenticate_user_from_private_token!" do
+    controller(ApplicationController) do
+      def index
+        render text: "authenticated"
+      end
+    end
+
+    let(:user) { create(:user) }
+
+    it "logs the user in when the 'authenticity_token' param is populated with the private token" do
+      get :index, authenticity_token: user.private_token
+      expect(response.status).to eq(200)
+      expect(response.body).to eq("authenticated")
+    end
+
+    it "logs the user in when the 'private_token' param is populated with the private token" do
+      get :index, private_token: user.private_token
+      expect(response.status).to eq(200)
+      expect(response.body).to eq("authenticated")
+    end
+
+    it "logs the user in when the 'PRIVATE-TOKEN' header is populated with the private token" do
+      @request.headers['PRIVATE-TOKEN'] = user.private_token
+      get :index
+      expect(response.status).to eq(200)
+      expect(response.body).to eq("authenticated")
+    end
+
+    it "doesn't log the user in otherwise" do
+      @request.headers['PRIVATE-TOKEN'] = "token"
+      get :index, private_token: "token", authenticity_token: "token"
+      expect(response.status).to_not eq(200)
+      expect(response.body).to_not eq("authenticated")
+    end
+  end
+
+  describe "#authenticate_user_from_personal_access_token!" do
+    controller(ApplicationController) do
+      def index
+        render text: 'authenticated'
+      end
+    end
+
+    let(:user) { create(:user) }
+    let(:personal_access_token) { create(:personal_access_token, user: user) }
+
+    it "logs the user in when the 'personal_access_token' param is populated with the personal access token" do
+      get :index, personal_access_token: personal_access_token.token
+      expect(response.status).to eq(200)
+      expect(response.body).to eq('authenticated')
+    end
+
+    it "logs the user in when the 'PERSONAL_ACCESS_TOKEN' header is populated with the personal access token" do
+      @request.headers["PERSONAL_ACCESS_TOKEN"] = personal_access_token.token
+      get :index
+      expect(response.status).to eq(200)
+      expect(response.body).to eq('authenticated')
+    end
+
+    it "doesn't log the user in otherwise" do
+      get :index, personal_access_token: "token"
+      expect(response.status).to_not eq(200)
+      expect(response.body).to_not eq('authenticated')
+    end
+  end
 end