[v3.1] Email templates

[anhskohbo]

• [x] New Booking (admin)
• [x] Cancelled Booking (admin)
• [x] Failed Booking (admin)
• [x] Reserved Booking
• [x] Processing Booking
• [x] Completed Booking

[anhskohbo]

@ndoublehwp How it work, see:

https://github.com/awethemes/awebooking/blob/v3.1/inc/Email/Templates/Customer_Note.php

[anhskohbo]

@ndoublehwp Check lại phần desc (mở woo ra copy) và placeholders ở mỗi email