Change loadingscreen default background color

__tests__/ui/components/loadingScreen/__snapshots__/LoadingScreen.spec.js.snap

@@ -5,6 +5,7 @@ exports[`LoadingScreen component renders correctly 1`] = `
   style={
     Object {
       "alignItems": "center",
+      "backgroundColor": "#FFFFFF",
       "flex": 1,
       "justifyContent": "center",
     }

app/ui/components/loadingScreen/style/LoadingScreen.js

-import { StyleSheet } from 'react-native';
+import Colors from '../../../style/Colors';
+import StyleSheet from '../../../style/StyleSheet';
 
 const styles = StyleSheet.create({
   indicatorView: {
     justifyContent: 'center',
     alignItems: 'center',
     flex: 1,
+    backgroundColor: Colors.white,
   },
 });