added missing package immutable

Author: timarney

package.json

@@ -3,18 +3,19 @@
   "version": "0.1.0",
   "private": true,
   "dependencies": {
+    "google-map-react": "0.24.0",
+    "immutable": "^3.8.1",
+    "points-cluster": "0.1.4",
+    "prop-types": "15.5.10",
     "react": "^15.6.1",
     "react-dom": "^15.6.1",
     "react-scripts": "1.0.10",
-    "styled-components": "2.1.0",
-    "points-cluster": "0.1.4",
-    "google-map-react": "0.24.0",
-    "prop-types": "15.5.10"
+    "styled-components": "2.1.0"
   },
   "scripts": {
     "start": "react-scripts start",
     "build": "react-scripts build",
     "test": "react-scripts test --env=jsdom",
     "eject": "react-scripts eject"
   }
-}
+}

yarn.lock

@@ -2987,7 +2987,7 @@ ignore@^3.2.0:
   version "3.3.3"
   resolved "https://registry.yarnpkg.com/ignore/-/ignore-3.3.3.tgz#432352e57accd87ab3110e82d3fea0e47812156d"
 
-immutable@3.8.1:
+immutable@^3.8.1:
   version "3.8.1"
   resolved "https://registry.yarnpkg.com/immutable/-/immutable-3.8.1.tgz#200807f11ab0f72710ea485542de088075f68cd2"
 
@@ -4862,7 +4862,7 @@ promise@7.1.1, promise@^7.1.1:
   dependencies:
     asap "~2.0.3"
 
-prop-types@^15.5.10, prop-types@^15.5.4:
+prop-types@15.5.10, prop-types@^15.5.10, prop-types@^15.5.4:
   version "15.5.10"
   resolved "https://registry.yarnpkg.com/prop-types/-/prop-types-15.5.10.tgz#2797dfc3126182e3a95e3dfbb2e893ddd7456154"
   dependencies: