Add support for tokens (for payment)

[Klakurka]

Scope:

• Add a new token config parameter which will take in a token ID.
• Grab the token icon for the QR code.
• Listen for the (SLP/ALP) token instead of straight XEC.

Until we get a specific request for it, we'll v2 support for Cashtokens. It shouldn't be much more work since we're using BCHC.

[Klakurka]

We do now have a need for this.