Fix handling of improperly-encoded DER signatures to match OpenSSL

This always reads variables in DER signatures as positive, even
when they are encoded as negative.
Implement PUSHDATA4 in Script.parse
Fix Utils.decodeMPI and add a Utils.encodeMPI
Add Matt to the AUTHORS file
Change the wallet to relay tx confidence events instead of generating them itself, which is a bit cleaner. Centralize state that needs to be rebuilt after a Java deserialization. Resolves issue 235.
Serialize the broadcastBy set for each transaction. Resolves issue 237.
Change AUTHORS file.
Another pass at the auto-save code. Resolves issue 246.
Mark JDK SLF adapter as scope test. Resolves issue 231.
Delete a bit of dead code in PeerGroup.
Use JDK logging in the examples module.
Add a convenience API to TCPNetworkConnection to get a handshaked connection. Update JavaDocs.
Add a TODO in PeerGroup
Use the new TCPNetworkConnection.connectTo API in PrintPeers, act as an example of the Guava futures API too.
JavaDoc improvements and other minor tweaks. Remove a few things that are not really meant to be public APIs.
Use current time as unit test chain genesis block time. Resolves a weird issue where the unit tests suddenly broke as the previous unit test genesis time was equal to testnet genesis time.
Re-organize the wallet sending APIs to take a SendRequest. Full details of the API changes are sent to the list.
Update WalletTool to new send API.
Fix a NullPointerException introduced by the TCPNetworkConnection helper APIs.
Implement the ability to explicitly set a fee in the Wallet.SendRequest. Does not yet auto-calculate the correct fees. Resolves issue 45. Resolves issue 245.