CORE-789: In `rippleWalletAddTransfer` handle a 'self-transfer'
CORE-789: In `rippleWalletAddTransfer` handle a 'self-transfer'

If a 'self-transfer' the balance changes only by the fee.

breadwallet/breadwallet-core,breadwallet/breadwallet-core,breadwallet/breadwallet-core,breadwallet/breadwallet-core,breadwallet/breadwallet-core,breadwallet/breadwallet-core