skycoin-cli transaction, error: index out of range

When I run the command `skycoin cli-transaction` with out arguments raise next error:
```
panic: runtime error: index out of range

goroutine 1 [running]:
github.com/skycoin/skycoin/src/cli.transactionCmd.func1(0xc420323680, 0xd2b448, 0x0, 0x0, 0x0, 0x0)
$GOPATH/src/github.com/skycoin/skycoin/src/cli/transaction.go:28 +0x1b2
github.com/skycoin/skycoin/vendor/github.com/spf13/cobra.(*Command).execute(0xc420323680, 0xd2b448, 0x0, 0x0, 0xc420323680, 0xd2b448)
$GOPATH/src/github.com/skycoin/skycoin/vendor/github.com/spf13/cobra/command.go:762 +0x468
github.com/skycoin/skycoin/vendor/github.com/spf13/cobra.(*Command).ExecuteC(0xc420316000, 0xc420325400, 0xc420325680, 0xc420325900)
$GOPATH/src/github.com/skycoin/skycoin/vendor/github.com/spf13/cobra/command.go:852 +0x30a
github.com/skycoin/skycoin/vendor/github.com/spf13/cobra.(*Command).Execute(0xc420316000, 0x1a, 0xc420312010)
$GOPATH/src/github.com/skycoin/skycoin/vendor/github.com/spf13/cobra/command.go:800 +0x2b
main.main()
$GOPATH/src/github.com/skycoin/skycoin/cmd/cli/cli.go:26 +0x19e

```

Start at src/cli/transaction.go:28, identified by the stack trace, and run `skycoin cli-transaction` without arguments to reproduce the panic. Determine the command's expected behavior for missing arguments and verify that the command reports the input problem without an index-out-of-range panic.

Written by the indexing model from the issue text.