Restrict line length to 80 characters (adjust eslint rule)

Code lines restricted to 80 characters lets you use many horizontal split screens in your editor which is nice.

diff --git a/.eslintrc b/.eslintrc
index c9d84498..6d8085f9 100644
--- a/.eslintrc
+++ b/.eslintrc
@@ -10,6 +10,13 @@
     "jest"
   ],
   "rules": {
+    "max-len": ["error", 80, 2, {
+      ignoreUrls: true,
+      ignoreComments: false,
+      ignoreRegExpLiterals: true,
+      ignoreStrings: false,
+      ignoreTemplateLiterals: false,
+    }],
     // FIXME: Deprecate use of findDOMNode https://github.com/mozilla/addons-frontend/issues/968
     "react/no-find-dom-node": "off",
   },

We discussed it here: https://github.com/mozilla/addons-frontend/pull/3036#discussion_r136206566

Unfortunately, yarn eslint -- --fix cannot help with this.

Please ask before fixing this issue as it will be hard to review and could introduce merge conflicts.

[muffinresearch]

Alright I’ll put a patch together to see what it look like - that’ll be a good way for everyone to see if they’re on board with Prettier’s output as a starting point.

[kumar303]

As a stepping stone we could maybe do ignoreStrings: true and ignoreTemplateLiterals: true.