reduce module interdependancy, /client refactor (#4415)

* abstract staking BuildCreateValidatorMsg, genutil defines its own flags

* client/ refactor

* staking move keys from keeper to types

client/keys/root.go

@@ -3,7 +3,7 @@ package keys
 import (
 	"github.com/spf13/cobra"
 
-	"github.com/cosmos/cosmos-sdk/client"
+	"github.com/cosmos/cosmos-sdk/client/flags"
 )
 
 // Commands registers a sub-tree of commands to interact with
@@ -23,7 +23,7 @@ func Commands() *cobra.Command {
 		addKeyCommand(),
 		listKeysCmd(),
 		showKeysCmd(),
-		client.LineBreak,
+		flags.LineBreak,
 		deleteKeyCommand(),
 		updateKeyCommand(),
 		parseKeyStringCommand(),