Upgrade all dev dependencies (#223)

Author: danez

package.json

@@ -43,18 +43,18 @@
   },
   "devDependencies": {
     "babel-cli": "^6.9.0",
-    "babel-eslint": "^7.0.0",
-    "babel-jest": "^20.0.3",
+    "babel-eslint": "^8.0.1",
+    "babel-jest": "^21.2.0",
     "babel-plugin-transform-object-rest-spread": "^6.23.0",
     "babel-plugin-transform-runtime": "^6.9.0",
     "babel-preset-env": "^1.1.8",
     "babel-preset-flow": "^6.23.0",
     "cross-spawn": "^5.0.0",
     "eslint": "^4.3.0",
-    "flow-bin": "^0.53.1",
-    "jest": "^20.0.4",
-    "jest-diff": "^20.0.3",
-    "jest-matcher-utils": "^20.0.3",
+    "flow-bin": "^0.57.3",
+    "jest": "^21.2.1",
+    "jest-diff": "^21.2.1",
+    "jest-matcher-utils": "^21.2.1",
     "rimraf": "^2.3.2",
     "temp": "^0.8.1"
   },