Change to dark theme

ui/src/App.js

@@ -3,14 +3,14 @@ import React from 'react'
 import { Admin, Resource } from 'react-admin'
 import dataProvider from './dataProvider'
 import authProvider from './authProvider'
-import { Login, Layout, LightTheme } from './layout'
+import { Login, Layout, DarkTheme } from './layout'
 import user from './user'
 import song from './song'
 import album from './album'
 import artist from './artist'
 import { createMuiTheme } from '@material-ui/core/styles'
 
-const theme = createMuiTheme(LightTheme)
+const theme = createMuiTheme(DarkTheme)
 
 const App = () => (
   <Admin