Remote following success page (#4129)

* Added a success page to remote following
Includes follow-through links to web (the old redirect target) and back to the remote user's profile

* Use Account.new in spec instead of a fake with only id
(fixes spec)

* Fabricate(:account) over Account.new

* Remove self from the success text
(and all HTML with it)

spec/controllers/authorize_follows_controller_spec.rb

@@ -94,7 +94,7 @@ describe AuthorizeFollowsController do
       end
 
       it 'follows account when found' do
-        target_account = double(id: '123')
+        target_account = Fabricate(:account)
         result_account = double(target_account: target_account)
         service = double
         allow(FollowService).to receive(:new).and_return(service)
@@ -103,7 +103,7 @@ describe AuthorizeFollowsController do
         post :create, params: { acct: 'acct:user@hostname' }
 
         expect(service).to have_received(:call).with(account, 'user@hostname')
-        expect(response).to redirect_to(web_url('accounts/123'))
+        expect(response).to render_template(:success)
       end
     end
   end