Improve linting.

- Code is very out-of-date with proper style.
- Fix so it at least shows errors with modern eslint.
- Disable some rules with too many hits for current style.

.eslintrc.js

@@ -9,13 +9,16 @@ module.exports = {
     'digitalbazaar'
   ],
   parserOptions: {
-    ecmaVersion: 5
+    ecmaVersion: 5,
+    sourceType: 'script'
   },
   rules: {
     // overrides to support ES5, remove when updated to ES20xx
     'no-unused-vars': 'warn',
     'no-var': 'off',
     'object-shorthand': 'off',
-    'prefer-const': 'off'
+    'prefer-const': 'off',
+    // fix when code is globally reformatted
+    'max-len': 'off'
   }
 };