Add eslint-plugin-jsx-a11y (#1651)

* Add eslint-plugin-jsx-a11y.

* Fix npm script.

* Adjust npm scripts so test also runs lint.

* Fix existing lint errors.

* Don't break on a11y issues.

* Add role and tabIndex.

* Add vim and Mac files to .gitignore and .dockerignore.

* Handle htmlFor (partially), a that's actually a button.

* Fix missing tabIndex.

* Add cursor:pointer to load-more

* Revert change to load_more.

* Fixes based on review.

* Update yarn.lock.

* Don't try to install fsevents on Linux (hides warning noise).

.eslintrc

@@ -8,7 +8,8 @@
   "parser": "babel-eslint",
 
   "plugins": [
-    "react"
+    "react",
+    "jsx-a11y"
   ],
 
   "parserOptions": {
@@ -43,9 +44,36 @@
     "no-mixed-spaces-and-tabs": 1,
     "no-nested-ternary": 1,
     "no-trailing-spaces": 1,
-    "react/wrap-multilines": 2,
+
+    "react/jsx-wrap-multilines": 2,
     "react/self-closing-comp": 2,
     "react/prop-types": 2,
-    "react/no-multi-comp": 0
+    "react/no-multi-comp": 0,
+
+    "jsx-a11y/accessible-emoji": 1,
+    "jsx-a11y/anchor-has-content": 1,
+    "jsx-a11y/aria-activedescendant-has-tabindex": 1,
+    "jsx-a11y/aria-props": 1,
+    "jsx-a11y/aria-proptypes": 1,
+    "jsx-a11y/aria-role": 1,
+    "jsx-a11y/aria-unsupported-elements": 1,
+    "jsx-a11y/heading-has-content": 1,
+    "jsx-a11y/href-no-hash": 1,
+    "jsx-a11y/html-has-lang": 1,
+    "jsx-a11y/iframe-has-title": 1,
+    "jsx-a11y/img-has-alt": 1,
+    "jsx-a11y/img-redundant-alt": 1,
+    "jsx-a11y/label-has-for": 1,
+    "jsx-a11y/mouse-events-have-key-events": 1,
+    "jsx-a11y/no-access-key": 1,
+    "jsx-a11y/no-distracting-elements": 1,
+    "jsx-a11y/no-onchange": 1,
+    "jsx-a11y/no-redundant-roles": 1,
+    "jsx-a11y/onclick-has-focus": 1,
+    "jsx-a11y/onclick-has-role": 1,
+    "jsx-a11y/role-has-required-aria-props": 1,
+    "jsx-a11y/role-supports-aria-props": 1,
+    "jsx-a11y/scope": 1,
+    "jsx-a11y/tabindex-no-positive": 1
   }
 }