cmd/baseserver, */rest: allow baseserver to choose which handlers to use

Make handlers easily configurable to use in cmd/baseserver/main.go.
This way client users can trivially change what functionality they'd
like.
It involves moving ServeCmd out of client/rest to */main.go
and lets client/rest become a bazaar for available mux.Router
registrars.

Updates #200

cmd/baseserver/main.go

@@ -1,13 +1,18 @@
 package main
 
 import (
+	"fmt"
 	"log"
+	"net/http"
 	"os"
 
+	"github.com/gorilla/mux"
 	"github.com/spf13/cobra"
+	"github.com/spf13/viper"
 
 	"github.com/tendermint/basecoin/client/commands"
 	rest "github.com/tendermint/basecoin/client/rest"
+	coinrest "github.com/tendermint/basecoin/modules/coin/rest"
 	"github.com/tendermint/tmlibs/cli"
 )
 
@@ -17,12 +22,59 @@ var srvCli = &cobra.Command{
 	Long:  `Baseserver presents  a nice (not raw hex) interface to the basecoin blockchain structure.`,
 }
 
+var serveCmd = &cobra.Command{
+	Use:   "serve",
+	Short: "Serve the light REST client for tendermint",
+	Long:  "Access basecoin via REST",
+	RunE:  serve,
+}
+
+const (
+	envPortFlag = "port"
+	defaultAlgo = "ed25519"
+)
+
+func init() {
+	_ = serveCmd.PersistentFlags().Int(envPortFlag, 8998, "the port to run the server on")
+}
+
+func serve(cmd *cobra.Command, args []string) error {
+	router := mux.NewRouter()
+
+	routeRegistrars := []func(*mux.Router) error{
+		// rest.Keys handlers
+		rest.NewDefaultKeysManager(defaultAlgo).RegisterAllCRUD,
+
+		// Coin send handler
+		coinrest.RegisterCoinSend,
+		// Coin query account handler
+		coinrest.RegisterQueryAccount,
+
+		// Basecoin sign transactions handler
+		rest.RegisterSignTx,
+		// Basecoin post transaction handler
+		rest.RegisterPostTx,
+	}
+
+	for _, routeRegistrar := range routeRegistrars {
+		if err := routeRegistrar(router); err != nil {
+			log.Fatal(err)
+		}
+	}
+
+	port := viper.GetInt(envPortFlag)
+	addr := fmt.Sprintf(":%d", port)
+
+	log.Printf("Serving on %q", addr)
+	return http.ListenAndServe(addr, router)
+}
+
 func main() {
 	commands.AddBasicFlags(srvCli)
 
 	srvCli.AddCommand(
 		commands.InitCmd,
-		rest.ServeCmd,
+		serveCmd,
 	)
 
 	// TODO: Decide whether to use $HOME/.basecli for compatibility