Refactor media upload

Use Upload Media logic from Pleroma

Backend changes for picture upload

Move AS <-> Model conversion to separate module

Front changes

Downgrade apollo-client: https://github.com/Akryum/vue-apollo/issues/577

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

js/src/App.vue

@@ -91,6 +91,7 @@ export default class App extends Vue {
   @import "~buefy/src/scss/components/form";
   @import "~buefy/src/scss/components/modal";
   @import "~buefy/src/scss/components/tag";
+  @import "~buefy/src/scss/components/upload";
   @import "~buefy/src/scss/utils/_all";
 
 .router-enter-active,