Added ETA Button with notifications, flash feedback and localization

[antoniozh]

Added ETA feature. Users will need to enable it under 'Cards'

[ryanmitchell]

Thanks for the PR. I need to have a think about whether it’s right to merge this as it clashes with my (paid) order approver add on.

[antoniozh]

Yeah, we came up with this since the order notifier add on we bought seemed to break our printers. Not sure if it's the case in general though