Improve data model & fix tests

app/package-lock.json

@@ -46,6 +46,47 @@
         "warning": "^4.0.1"
       }
     },
+    "@material-ui/icons": {
+      "version": "3.0.1",
+      "resolved": "https://registry.npmjs.org/@material-ui/icons/-/icons-3.0.1.tgz",
+      "integrity": "sha512-1kNcxYiIT1x8iDPEAlgmKrfRTIV8UyK6fLVcZ9kMHIKGWft9I451V5mvSrbCjbf7MX1TbLWzZjph0aVCRf9MqQ==",
+      "dev": true,
+      "requires": {
+        "@babel/runtime": "7.0.0",
+        "recompose": "^0.29.0"
+      },
+      "dependencies": {
+        "@babel/runtime": {
+          "version": "7.0.0",
+          "resolved": "https://registry.npmjs.org/@babel/runtime/-/runtime-7.0.0.tgz",
+          "integrity": "sha512-7hGhzlcmg01CvH1EHdSPVXYX1aJ8KCEyz6I9xYIi/asDtzBPMyMhVibhM/K6g/5qnKBwjZtp10bNZIEFTRW1MA==",
+          "dev": true,
+          "requires": {
+            "regenerator-runtime": "^0.12.0"
+          }
+        },
+        "hoist-non-react-statics": {
+          "version": "2.5.5",
+          "resolved": "https://registry.npmjs.org/hoist-non-react-statics/-/hoist-non-react-statics-2.5.5.tgz",
+          "integrity": "sha512-rqcy4pJo55FTTLWt+bU8ukscqHeE/e9KWvsOW2b/a3afxQZhwkQdT1rPPCJ0rYXdj4vNcasY8zHTH+jF/qStxw==",
+          "dev": true
+        },
+        "recompose": {
+          "version": "0.29.0",
+          "resolved": "https://registry.npmjs.org/recompose/-/recompose-0.29.0.tgz",
+          "integrity": "sha512-J/qLXNU4W+AeHCDR70ajW8eMd1uroqZaECTj6qqDLPMILz3y0EzpYlvrnxKB9DnqcngWrtGwjXY9JeXaW9kS1A==",
+          "dev": true,
+          "requires": {
+            "@babel/runtime": "^7.0.0",
+            "change-emitter": "^0.1.2",
+            "fbjs": "^0.8.1",
+            "hoist-non-react-statics": "^2.3.1",
+            "react-lifecycles-compat": "^3.0.2",
+            "symbol-observable": "^1.0.4"
+          }
+        }
+      }
+    },
     "@material-ui/utils": {
       "version": "3.0.0-alpha.2",
       "resolved": "https://registry.npmjs.org/@material-ui/utils/-/utils-3.0.0-alpha.2.tgz",