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/bluetooth-serial/index.ts

@@ -13,7 +13,7 @@ import { Observable } from 'rxjs/Observable';
  *
  *
  * // Write a string
- * this.bluetoothSerial.write("hello world").then(success, failure);
+ * this.bluetoothSerial.write('hello world').then(success, failure);
  *
  * // Array of int or bytes
  * this.bluetoothSerial.write([186, 220, 222]).then(success, failure);