Merge PR #2874: gaiad gentx subcommands refactoring

* gaiad gentx subcommands refactoring

- Replace STDIN/STDOUT redirection in `gaiad gentx` with subcommands
  command line options to redirect streams to file since viper does
  not handle redirection well.
- Use `BuildCreateValidatorMsg` to build a `MsgCreateValidator` rather
  than redirecting to `gaiacli tx stake create-validator`.
- `PrintUnsignedStdTx` now takes an `io.Writer` object.
- Mark `--pubkey`, `--amount` and `--moniker` as required flags
  instead of validating them manually.
- Use stake.NewDescription() to make a new Description - ref #2835

* Refresh PENDING.md

x/slashing/client/cli/tx.go

@@ -7,6 +7,7 @@ import (
 	sdk "github.com/cosmos/cosmos-sdk/types"
 	authtxb "github.com/cosmos/cosmos-sdk/x/auth/client/txbuilder"
 	"github.com/cosmos/cosmos-sdk/x/slashing"
+	"os"
 
 	"github.com/spf13/cobra"
 )
@@ -30,7 +31,7 @@ func GetCmdUnjail(cdc *codec.Codec) *cobra.Command {
 
 			msg := slashing.NewMsgUnjail(sdk.ValAddress(valAddr))
 			if cliCtx.GenerateOnly {
-				return utils.PrintUnsignedStdTx(txBldr, cliCtx, []sdk.Msg{msg}, false)
+				return utils.PrintUnsignedStdTx(os.Stdout, txBldr, cliCtx, []sdk.Msg{msg}, false)
 			}
 			return utils.CompleteAndBroadcastTxCli(txBldr, cliCtx, []sdk.Msg{msg})
 		},