Fix props warning in MemberList

app/actions/members.js

@@ -5,7 +5,7 @@ export const FAILURE = 'MEMBERS_FAILURE';
 export const MORE = 'MEMBERS_MORE';
 export const MORE_SUCCESS = 'MEMBERS_MORE_SUCCESS';
 
-export function members(keywords = null) {
+export function members(keywords = '') {
   return {
     type: MEMBERS,
     payload: { keywords },

app/ui/screens/memberList/MemberListScreenContainer.js

@@ -11,7 +11,7 @@ const mapStateToProps = state => ({
 });
 
 const mapDispatchToProps = dispatch => ({
-  loadMembers: (keywords = null) => dispatch(memberActions.members(keywords)),
+  loadMembers: (keywords = '') => dispatch(memberActions.members(keywords)),
   loadMoreMembers: url => dispatch(memberActions.more(url)),
 });