meta: introduce Cypress end-to-end testing (via #4827)

* `test/e2e` -> `test/e2e-selenium`

* add Cypress

* ESLint fixes

* MOAR cypress

* `integration` -> `tests`

* wire Cypress up to a hot e2e server

* linter fixes

* don't run in CI

.eslintrc

@@ -1,52 +1,36 @@
-{
-  "parser": "babel-eslint",
-
-  "env": {
-    "browser": true,
-    "node": true,
-    "es6": true
-  },
-
-  "parserOptions": {
-    "ecmaFeatures": {
-      "jsx": true
-    }
-  },
-
-  "extends": [
-    "eslint:recommended",
-    "plugin:react/recommended"
-  ],
-
-  "plugins": [
-    "react",
-    "mocha",
-    "import"
-  ],
-
-  "settings": {
-    "react": {
-      "pragma": "React",
-      "version": "15.0"
-    }
-  },
-
-  "rules": {
-    "semi": [2, "never"],
-    "strict": 0,
-    "quotes": [2, "double", { "allowTemplateLiterals": true }],
-    "no-unused-vars": 2,
-    "no-multi-spaces": 1,
-    "camelcase": 1,
-    "no-use-before-define": [2,"nofunc"],
-    "no-underscore-dangle": 0,
-    "no-unused-expressions": 1,
-    "comma-dangle": 0,
-    "no-console": ["error", { allow: ["warn", "error"] }],
-    "react/jsx-no-bind": 1,
-    "react/jsx-no-target-blank": 2,
-    "react/display-name": 0,
-    "mocha/no-exclusive-tests": "error",
-    "import/no-extraneous-dependencies": [2]
-  }
-}
+parser: babel-eslint
+env:
+  browser: true
+  node: true
+  es6: true
+parserOptions:
+  ecmaFeatures:
+    jsx: true
+extends:
+  - eslint:recommended
+  - plugin:react/recommended
+plugins:
+  - react
+  - mocha
+  - import
+settings:
+  react:
+    pragma: React
+    version: '15.0'
+rules:
+  semi: [2, never]
+  strict: 0
+  quotes: [2, double, { allowTemplateLiterals: true }]
+  no-unused-vars: 2
+  no-multi-spaces: 1
+  camelcase: 1
+  no-use-before-define: [2, nofunc]
+  no-underscore-dangle: 0
+  no-unused-expressions: 1
+  comma-dangle: 0
+  no-console: [2, { allow: [warn, error] }]
+  react/jsx-no-bind: 1
+  react/jsx-no-target-blank: 2
+  react/display-name: 0
+  mocha/no-exclusive-tests: 2
+  import/no-extraneous-dependencies: 2