core/vm: don't include contract deployer bytecode in AccessWitness or charge witness access costs for it (#54)

core/vm/contract.go

@@ -58,6 +58,9 @@ type Contract struct {
 	CodeAddr *common.Address
 	Input    []byte
 
+	// is the execution frame represented by this object a contract deployment 
+	IsDeployment bool
+
 	Gas   uint64
 	value *big.Int
 }