Upgraded deps, including babel plugins (#48)

Author: erikras

.babelrc

@@ -1,20 +1,39 @@
 {
   "presets": [
     [
-      "env",
+      "@babel/preset-env",
       {
         "targets": {
           "node": "8"
         }
       }
     ],
-    "react",
-    "stage-2"
+    "@babel/preset-react",
+    "@babel/preset-flow"
   ],
   "env": {
     "test": {
-      "plugins": ["transform-react-jsx-source", "istanbul"]
+      "plugins": [
+        "@babel/plugin-transform-react-jsx-source",
+        "istanbul"
+      ]
     }
   },
-  "plugins": ["transform-flow-strip-types"]
+  "plugins": [
+    "@babel/plugin-transform-flow-strip-types",
+    "@babel/plugin-syntax-dynamic-import",
+    "@babel/plugin-syntax-import-meta",
+    "@babel/plugin-proposal-class-properties",
+    "@babel/plugin-proposal-json-strings",
+    [
+      "@babel/plugin-proposal-decorators",
+      {
+        "legacy": true
+      }
+    ],
+    "@babel/plugin-proposal-function-sent",
+    "@babel/plugin-proposal-export-namespace-from",
+    "@babel/plugin-proposal-numeric-separator",
+    "@babel/plugin-proposal-throw-expressions"
+  ]
 }