Married HD wallets: Bloom filter adjustments

Pull request: #115
Based on design notes:
https://groups.google.com/forum/#!msg/bitcoinj/Uxl-z40OLuQ/e2m4mEWR6gMJ
Close connections in H2FullPrunedBlockStore
Add encrypt/decrypt command to the WalletTool help text.
HD Wallets: redo key rotation, it's no longer automatic and expects the wallet app to poll for maintenance transactions. Deterministic keys now inherit the creation time of their parent.