Wallets: Add KnC Wallet for iOS

Adding KnC Wallet for iOS to choose-your-wallet.html


KnC Wallet is a [SPV](https://en.bitcoin.it/wiki/Thin_Client_Security#Header-Only_Clients),
[BIP32](https://github.com/bitcoin/bips/blob/master/bip-0032.mediawiki)
deterministic bitcoin wallet for iOS.

KnC Wallet is open source and available under the terms of the MIT license. It is a fork of the excellent [breadwallet](https://github.com/voisine/breadwallet).

Our iOS wallet has all the same functionality as our android version, such as integration with our KnC Directory and onename.io.