1) Update the full stores to return UTXO transactions.
2) The wallet can now use a UTXOProvider to create spends.
3) Updated MySQL field blob size.  It's capacity isn't sufficient.
4) Updated internal objects to be able to cope with a null parent tx (spend free standing outputs).
Wallet.loadFromFile takes WalletExtensions
Update AUTHORS file
Rename MemoryPool to TxConfidencePool and make singleton
Remove tx from TransactionConfidence
Mark unrelated flaky test
introduce a Context object vended by AbstractBlockChain

have it hold the confidencePool
Clean up JavaDoc for deprecated PeerGroup.getConfidencePool
rename TxConfidencePool to TxConfidenceTable
Java 8 syntax cleanup