[Superhack-01]Add opcode to geth: experiment with constant return value

[jeff0723]

Description:
This PR added an opcode INFERCALL to geth, including modifying the below file:

1. Add an execution function to core/vm/instruction.go
2. Add an opcode to core/vm/opcodes.go
3. Add an dynamic gas function which return constant value to core/vm/gas_table.go
4. Register new opcode in core/vm/jump_table.go

Todo:
Run this updated version of geth and write a smart contract to check if it is working.