Upgrade Editor – Slate 0.44 / RME 8.0.0 (#863)

* Upgrade Slate

* Normalization

* Remove dupe dep

* Fixes placeholders

* Image uploading fixed

* Verbose but solid placeholder handling

* RME 8.0.0

* Fixes: Ability to delete embeds

app/components/Editor/Editor.js

@@ -7,8 +7,6 @@ import Embed from './Embed';
 import embeds from '../../embeds';
 
 type Props = {
-  titlePlaceholder?: string,
-  bodyPlaceholder?: string,
   defaultValue?: string,
   readOnly?: boolean,
   disableEmbeds?: boolean,