Cross platform virtual machine implementation (#60)

* Virtual machine for the NEO blockhain.

* fixed big.Int numeric operation pointer issue.

* added appcall

* Added README for vm package.

* removed main.go

* started VM cli (prompt) integration

* added support for printing the stack.

* moved cli to vm package

* fixed vet errors

* updated readme

* added more test for VM and fixed some edge cases.

* bumped version -> 0.37.0

cli/main.go

@@ -5,6 +5,7 @@ import (
 
 	"github.com/CityOfZion/neo-go/cli/server"
 	"github.com/CityOfZion/neo-go/cli/smartcontract"
+	"github.com/CityOfZion/neo-go/cli/vm"
 	"github.com/CityOfZion/neo-go/cli/wallet"
 	"github.com/urfave/cli"
 )
@@ -18,6 +19,7 @@ func main() {
 		server.NewCommand(),
 		smartcontract.NewCommand(),
 		wallet.NewCommand(),
+		vm.NewCommand(),
 	}
 
 	ctl.Run(os.Args)