Merge pull request #3681 from karalabe/usb-hidapi

accounts/usbwallet/ledger_hub.go

accounts/usbwallet/ledger_wallet.go

accounts/usbwallet/usbwallet.go

accounts/usbwallet/usbwallet_ios.go

vendor/github.com/karalabe/gousb/.gitignore

vendor/github.com/karalabe/gousb/.travis.yml

vendor/github.com/karalabe/gousb/LICENSE

vendor/github.com/karalabe/gousb/README.md

vendor/github.com/karalabe/gousb/appveyor.yml

vendor/github.com/karalabe/gousb/usb/config.go

vendor/github.com/karalabe/gousb/usb/constants.go

vendor/github.com/karalabe/gousb/usb/debug.go

vendor/github.com/karalabe/gousb/usb/descriptor.go

vendor/github.com/karalabe/gousb/usb/device.go

vendor/github.com/karalabe/gousb/usb/endpoint.go

vendor/github.com/karalabe/gousb/usb/error.go

vendor/github.com/karalabe/gousb/usb/iso.c

vendor/github.com/karalabe/gousb/usb/iso.go

vendor/github.com/karalabe/gousb/usb/misc.go

vendor/github.com/karalabe/gousb/usb/usb.go