style(): unify docs and spacing (#1448)

* typo(barcode-scanner): fixe circle lint error

* typo(docs):  Unified the documentations

In some plugins the typescript markup was missing.
I also unified the console.log string from console.log("hello") to console.log('Hello') so any plugin page look the same.

src/@ionic-native/plugins/backlight/index.ts

@@ -9,7 +9,7 @@ import { Plugin, Cordova, IonicNativePlugin } from '@ionic-native/core';
  * This plugin adds turning on/off the device backlight.
  *
  * @usage
- * ```
+ * ```typescript
  * import { Backlight } from '@ionic-native/backlight';
  *
  * constructor(private backlight: Backlight) { }