Breakpoint option for setting when the mobile layout gets triggered

The plugin has the tips switch to a mobile layout at ```768px``` by default, but in the case that I'm using it in I didn't need the mobile layout to be triggered until smaller than that, so I thought adding a ```breakpoint``` option to the settings would be helpful. If left untouched the default is still ```768px```, but if desired you can set your own:  
```
$('#joyride').joyride({
    breakpoint:600
})
```
Remember, this is a ```only screen and max-width()``` media query.