move prettier opts to .prettierrc (gatsbyjs#48)

* Create .prettierrc

* move prettier opts to .prettierrc

Author: pravdomil

.prettierrc

@@ -0,0 +1,5 @@
+{
+  "semi": false,
+  "singleQuote": true,
+  "trailingComma": "es5"
+}

package.json

@@ -16,7 +16,7 @@
   "scripts": {
     "build": "gatsby build",
     "develop": "gatsby develop",
-    "format": "prettier --trailing-comma es5 --no-semi --single-quote --write \"src/**/*.js\"",
+    "format": "prettier --write \"src/**/*.js\"",
     "test": "echo \"Error: no test specified\" && exit 1"
   },
   "devDependencies": {