Merge pull request #146 from JoshVorick/client

Divide client logic and user interface
add switch instruction
export bootstrapAddress
change example script inputs to functions
add TransactionScript
fix the bug that David already fixed
add error values to scriptapi
add Ping command
reorder some opcode inputs
update client
Merge pull request #147 from lukechampine/scripting

Basic client
fix bootstrapping
fix signed message encoding
fix nil big.Int decoding
Merge pull request #148 from lukechampine/scripting

fix signed message encoding
Add secret key gob encoding