Add capabilities attribute for printers and ticket option for print jobs

Added the capabilities response to the printer object and the ticket option for print jobs. 
Now its possible to send printer settings with the job. For example: 

```ruby
printer_options = { version: "1.0", print: { fit_to_page: {type: 3} } }.to_json
job = my_printer.print(content: url, content_type: "url", ticket: printer_options)
```