Merge pull request #78 from maraoz/bug/fix-node-Transaction

fix Transaction for node
migrating to buffertools best practices
added tests to Block and Peer, and migrated buffertools usage
fix buffertools in Transaction
migrating buffertools compare method and test
fixed various test problems
fixed concat references
fix buffertool's fill calls
fix reverse buffertools use
fix toHex use
fix Buffer.concat use