EtherSaleWallet

Contains two classes:
1. EtherSaleWallet
2. EtherSaleWalletDecoder

EtherSaleWallet is the POJO for the JSON ether sale wallet. 
EtherSaleWalletDecoder allows the decryption of the private ethereum key. Given you provide the right password. Tests for EtherSaleWalletDecoder are in EtherSaleWalletDecoderTest