Linting config adjustments

Per Antonio's comments on PR tahowallet#73
- promises instead of icky callbacks by using the browser global
- most of the prettier config was already default

.eslintrc

@@ -1,7 +1,7 @@
 {
   "extends": ["airbnb", "plugin:prettier/recommended"],
   "globals": {
-    "chrome": "readonly"
+    "browser": "readonly"
   },
   "rules": {
     "react/jsx-one-expression-per-line": [0],

.prettierrc

@@ -1,7 +1,3 @@
 {
-	"singleQuote": true,
-	"trailingComma": "es5",
-	"requirePragma": false,
-	"arrowParens": "always",
-	"prettier.eslintIntegration": true
+  "semi": false
 }