rpc: move Invoke to result package

It's just a data.

pkg/rpc/result/invoke.go

@@ -1,11 +1,12 @@
-package wrappers
+package result
 
 import (
 	"github.com/CityOfZion/neo-go/pkg/vm"
 )
 
-// InvokeResult is used as a wrapper to represent an invokation result.
-type InvokeResult struct {
+// Invoke represents code invocation result and is used by several RPC calls
+// that invoke functions, scripts and generic bytecode.
+type Invoke struct {
 	State       string `json:"state"`
 	GasConsumed string `json:"gas_consumed"`
 	Script      string `json:"script"`

pkg/rpc/server.go

@@ -486,12 +486,12 @@ func (s *Server) invokescript(reqParams Params) (interface{}, error) {
 
 // runScriptInVM runs given script in a new test VM and returns the invocation
 // result.
-func (s *Server) runScriptInVM(script []byte) *wrappers.InvokeResult {
+func (s *Server) runScriptInVM(script []byte) *result.Invoke {
 	vm, _ := s.chain.GetTestVM()
 	vm.SetGasLimit(s.config.MaxGasInvoke)
 	vm.LoadScript(script)
 	_ = vm.Run()
-	result := &wrappers.InvokeResult{
+	result := &result.Invoke{
 		State:       vm.State(),
 		GasConsumed: vm.GasConsumed().String(),
 		Script:      hex.EncodeToString(script),