Add dark mode (#33)

Closes: #18

This PR adds dark mode styling and an app setting to choose light, dark, or auto mode.

Reviewed-on: Georgi_Lab/ALVINN_f7#33

src/components/app.vue

@@ -1,6 +1,5 @@
 <template>
   <f7-app v-bind="f7params">
-
   <!-- Left panel with cover effect-->
   <f7-panel left cover>
     <f7-view>
@@ -45,6 +44,8 @@
       const f7params = {
         name: 'ALVINN', // App name
         theme: 'auto', // Automatic theme detection
+        //autoDarkTheme: !(localStorage.getItem('openhab.ui:theme.dark')),
+        darkMode: 'auto',
         colors: {
           primary: '#002f65',
         },