adds dependencies

package.json

@@ -48,6 +48,7 @@
     "html-webpack-plugin": "^3.2.0",
     "http-status": "^1.4.2",
     "image-size": "^0.7.5",
+    "is-hotkey": "^0.1.6",
     "isomorphic-fetch": "^2.2.1",
     "jest": "^25.3.0",
     "jsonwebtoken": "^8.5.1",
@@ -83,6 +84,9 @@
     "react-select": "^3.0.8",
     "sanitize-filename": "^1.6.3",
     "sharp": "^0.25.2",
+    "slate": "^0.58.1",
+    "slate-history": "^0.58.3",
+    "slate-react": "^0.58.2",
     "uglifyjs-webpack-plugin": "^1.3.0",
     "universal-cookie": "^3.1.0",
     "url-loader": "^1.0.1",