Update terminal title to 'Metro Bundler'

Summary:
I noticed in v0.50.0 all mentions of 'packager' were updated to 'Metro Bundler':

12eb04b

It seems like command which launches the bundler still sets the terminal title to 'React Packager'. This PR simply updates the title from 'React Packager' to 'Metro Bundler'.

Run `scripts/launchPackager.command`/`scripts/launchPackager.bat` and check title:

<img width="907" alt="screen shot 2018-01-05 at 14 02 53" src="https://user-images.githubusercontent.com/754498/34612337-3e93e8ca-f221-11e7-98f9-c5190674868e.png">

[GENERAL] [ENHANCEMENT] [./scripts]
Closes #17457

Differential Revision: D6673843

Pulled By: shergin

fbshipit-source-id: 65a072c3b79593391f257191b1372e7e9c8799f1

scripts/launchPackager.bat

@@ -6,7 +6,7 @@
 :: of patent rights can be found in the PATENTS file in the same directory.
 
 @echo off
-title React Packager
+title Metro Bundler
 node "%~dp0..\local-cli\cli.js" start
 pause
 exit

scripts/launchPackager.command

@@ -8,7 +8,7 @@
 # of patent rights can be found in the PATENTS file in the same directory.
 
 # Set terminal title
-echo -en "\033]0;React Packager\a"
+echo -en "\033]0;Metro Bundler\a"
 clear
 
 THIS_DIR=$(dirname "$0")