make invite an array instead of an object

When trying to clear the invite, because invite is currently an object, it’s getting the state’s existing invite re-applied via `defaultsDeep`. Making it an array should solve this issue

src/redux/messages.js

@@ -27,7 +27,7 @@ module.exports.getInitialState = function () {
         messages: {
             admin: [],
             social: [],
-            invite: {}
+            invite: []
         }
     };
 };
@@ -52,7 +52,7 @@ module.exports.messagesReducer = function (state, action) {
         }, state);
     case 'SET_SCRATCHER_INVITE':
         return defaultsDeep({
-            messages: {invite: action.invite}
+            messages: {invite: [action.invite]}
         }, state);
     case 'ADMIN_STATUS':
         return defaultsDeep({status: {admin: action.status}}, state);

src/views/messages/container.jsx

@@ -162,7 +162,7 @@ var mapStateToProps = function (state) {
         numNewMessages: state.messageCount.messageCount,
         messages: state.messages.messages.social,
         adminMessages: state.messages.messages.admin,
-        invite: state.messages.messages.invite,
+        invite: state.messages.messages.invite[0],
         messageOffset: state.messages.messages.socialOffset,
         requestStatus: state.messages.status
     };