move background to appearance tab

src/components/settings_modal/tabs/appearance_tab.vue

@@ -151,6 +151,49 @@
         </div>
       </div>
     </div>
+    <div class="setting-item">
+      <h2>{{ $t('settings.background') }}</h2>
+      <div class="banner-background-preview">
+        <img :src="user.background_image">
+        <button
+          v-if="!isDefaultBackground"
+          class="button-unstyled reset-button"
+          :title="$t('settings.reset_profile_background')"
+          @click="resetBackground"
+        >
+          <FAIcon
+            icon="times"
+            type="button"
+          />
+        </button>
+      </div>
+      <p>{{ $t('settings.set_new_background') }}</p>
+      <img
+        v-if="backgroundPreview"
+        class="banner-background-preview"
+        :src="backgroundPreview"
+      >
+      <div>
+        <input
+          type="file"
+          class="input"
+          @change="uploadFile('background', $event)"
+        >
+      </div>
+      <FAIcon
+        v-if="backgroundUploading"
+        class="uploading"
+        spin
+        icon="circle-notch"
+      />
+      <button
+        v-else-if="backgroundPreview"
+        class="btn button-default"
+        @click="submitBackground(background)"
+      >
+        {{ $t('settings.save') }}
+      </button>
+    </div>
     <div class="setting-item">
       <h2>{{ $t('settings.scale_and_layout') }}</h2>
       <div class="alert neutral theme-notice">