Rename Tests#test => Tests#test1
Radically simplify (tests fail)
Implement very simple balance summation
Introduce Ledger#total
Rename Account => Address
Re-introduce Transaction inputs and outputs
Refactor Transaction to consist of inputs and outputs
Rename Address=>Recipient, implement utxo balances
Implement unsecured in-memory ledger

Resolves #9
Fix Javadoc warning