Renamed PopupModal to PopupBox

refs https://github.com/TryGhost/Team/issues/1858

- PopupBox better reflects that it contains a Popup and is not a Popup
- In line with ContentBox, that contains the iframe with the comments content

apps/comments-ui/src/App.js

@@ -6,7 +6,7 @@ import AppContext from './AppContext';
 import {hasMode} from './utils/check-mode';
 import setupGhostApi from './utils/api';
 import ContentBox from './components/ContentBox';
-import PopupModal from './components/PopupModal';
+import PopupBox from './components/PopupBox';
 
 function AuthFrame({adminUrl, onLoad}) {
     const iframeStyle = {
@@ -305,7 +305,7 @@ export default class App extends React.Component {
                         <ContentBox done={done} />
                     </CommentsFrame>
                     <AuthFrame adminUrl={this.props.adminUrl} onLoad={this.initAdminAuth.bind(this)}/>
-                    <PopupModal />
+                    <PopupBox />
                 </AppContext.Provider>
             </SentryErrorBoundary>
         );

apps/comments-ui/src/components/PopupBox.js

@@ -3,7 +3,7 @@ import AppContext from '../AppContext';
 import Pages from '../pages';
 import GenericPopup from './popups/GenericPopup';
 
-export default function PopupModal(props) {
+export default function PopupBox(props) {
     const {popup} = useContext(AppContext);
 
     // To make sure we can properly animate a popup that goes away, we keep a state of the last visible popup