Pay with paper wallet via camera and NFC

[chill117]

Fixed:

• [x] After activating the camera to scan a paper wallet, cancel the camera by going back. Now an error is displayed because the app is trying to pay from a paper wallet that is an empty string.
• [x] NFC scanning wallet throws some error, preventing the payment from being accepted
• [x] When NFC is disabled (or unavailable) on the device, there are thrown errors. For example, the back/cancel buttons don't work anymore.
• [x] "Invalid network version" when trying to scan + pay with litecoin paper wallet (WIF)

Requires this pull-request on ct-api-server

[chill117]

Ready for review

[karliatto]

Tested in a device with no NFC it gives errors:

• when initializing the app it throws to the console:

  Failed to initialize the NfcPlugin NO_NFC phonegap-nfc.js:21

• When going to pay screen with the qr code:

  Uncaught TypeError: Object [object Object] has no method 'disableNfcReaderMode'

  The check this.doNFC() returns true, due to the fact that nfc object is not undefined, it does not contain function disableNfcReaderMode:

  ""{"addTagDiscoveredListener":"function","addMimeTypeListener":"function","addNdefListener":"function","addNdefFormatableListener":"function","write":"function","makeReadOnly":"function","share":"function","unshare":"function","handover":"function","stopHandover":"function","erase":"function","enabled":"function","removeTagDiscoveredListener":"function","removeMimeTypeListener":"function","removeNdefListener":"function","showSettings":"function","beginSession":"function","invalidateSession":"function","connect":"function","close":"function","transceive":"function","FLAG_READER_NFC_A":1,"FLAG_READER_NFC_B":2,"FLAG_READER_NFC_F":4,"FLAG_READER_NFC_V":8,"FLAG_READER_NFC_BARCODE":16,"FLAG_READER_SKIP_NDEF_CHECK":128,"FLAG_READER_NO_PLATFORM_SOUNDS":256,"readerMode":"function","disableReaderMode":"function","bytesToString":"function","stringToBytes":"function","bytesToHexString":"function"}""

  I guess the plugin "phonegap-nfc" tries to initialize and it creates the global object nfc, but without nfc functions.

[chill117]

Ready for review

[karliatto]

I tested paper wallet payment with BTC and LTC and it works for both.

I am wondering if it wouldn't be interesting to add a flag in the config file in order to easily disable this feature just in case we needed to release a version without it.

There is a conflict in package.json

[chill117]

Fixed conflicts