Add @types/react-router to dev dependencies

ui/package.json

@@ -40,6 +40,7 @@
     "@types/node": "^9.4.6",
     "@types/prop-types": "^15.5.2",
     "@types/react": "^16.0.38",
+    "@types/react-router": "^4.0.23",
     "autoprefixer": "^6.3.1",
     "babel-core": "^6.5.1",
     "babel-eslint": "6.1.2",

ui/yarn.lock

@@ -41,6 +41,10 @@
     "@types/cheerio" "*"
     "@types/react" "*"
 
+"@types/history@*":
+  version "4.6.2"
+  resolved "https://registry.yarnpkg.com/@types/history/-/history-4.6.2.tgz#12cfaba693ba20f114ed5765467ff25fdf67ddb0"
+
 "@types/jest@^22.1.4":
   version "22.2.0"
   resolved "https://registry.yarnpkg.com/@types/jest/-/jest-22.2.0.tgz#55ce83139f7ad1b48b414c3927746614c6963c0f"
@@ -57,6 +61,13 @@
   version "15.5.2"
   resolved "https://registry.yarnpkg.com/@types/prop-types/-/prop-types-15.5.2.tgz#3c6b8dceb2906cc87fe4358e809f9d20c8d59be1"
 
+"@types/react-router@^4.0.23":
+  version "4.0.23"
+  resolved "https://registry.yarnpkg.com/@types/react-router/-/react-router-4.0.23.tgz#d0509dcbdb1c686aed8f3d5cb186f42e5fbe7c2a"
+  dependencies:
+    "@types/history" "*"
+    "@types/react" "*"
+
 "@types/react@*", "@types/react@^16.0.38":
   version "16.0.40"
   resolved "https://registry.yarnpkg.com/@types/react/-/react-16.0.40.tgz#caabc2296886f40b67f6fc80f0f3464476461df9"