Add eslint import plugin to help detect unresolved paths

Most of the rules in the import plugin are only useful for projects
using purely ES6 imports. The `no-unresolved` rule works with mixed
CommonJS and ES6 though, so we at least benefit from that in the
meantime.

.eslintrc

@@ -30,7 +30,8 @@
     "mocha",
     "chai",
     "react",
-    "json"
+    "json",
+    "import"
   ],
 
   "globals": {
@@ -43,6 +44,7 @@
   },
 
   "rules": {
+    "import/no-unresolved": ["error", { "commonjs": true }],
     "no-restricted-globals": ["error", "event"],
     "accessor-pairs": 2,
     "arrow-spacing": [2, { "before": true, "after": true }],

package.json

@@ -189,6 +189,7 @@
     "@babel/preset-react": "^7.0.0",
     "@babel/register": "^7.5.5",
     "@sentry/cli": "^1.30.3",
+    "@storybook/addon-actions": "^5.2.6",
     "@storybook/addon-info": "^5.1.1",
     "@storybook/addon-knobs": "^3.4.2",
     "@storybook/react": "^5.1.1",
@@ -211,6 +212,7 @@
     "enzyme-adapter-react-15": "^1.0.6",
     "eslint": "^6.0.1",
     "eslint-plugin-chai": "0.0.1",
+    "eslint-plugin-import": "^2.18.2",
     "eslint-plugin-json": "^1.2.0",
     "eslint-plugin-mocha": "^5.0.0",
     "eslint-plugin-react": "^7.4.0",