allow to change color for asyncupload button

src/Bundle/ChillDocStoreBundle/Resources/public/vuejs/_components/AddAsyncUpload.vue

@@ -1,5 +1,5 @@
 <template>
-   <a class="btn btn-create" :title="$t(buttonTitle)" @click="openModal">
+   <a :class="btnClasses" :title="$t(buttonTitle)" @click="openModal">
       <span>{{ $t(buttonTitle) }}</span>
    </a>
    <teleport to="body">
@@ -96,10 +96,27 @@ export default {
       Modal
    },
    i18n,
-   props: [
-     'buttonTitle',
-     'options'
-   ],
+    props: {
+       buttonTitle: {
+           type: String,
+           default: 'Ajouter un document',
+       },
+        options: {
+            type: Object,
+            default: {
+                maxFiles: 1,
+                maxPostSize: 262144000, // 250MB
+                required: false,
+            }
+        },
+        btnClasses: {
+           type: Object,
+            default: {
+                btn: true,
+                'btn-create': true
+            }
+        }
+    },
    emits: ['addDocument'],
    data() {
       return {