Voting fix and further service api improvements

Fix voting code and added additional controller class for account manipulations. One AccountController will always manage one ArkAccount. More accounts will be grouped in Wallet.cs (TBD)

var accCtnrl = new AccountController("this is a top secret passphrase");

var result = accCtnrl.SendArk(satoshiAmount, "recepientAddress", "description", "top secret pass");
var result = accCtnrl.VoteForDelegate( votes, "top secret pass");