Modify iOSShell-gyp to generate unique bundle identifier

experimental/iOSShell/iOSShell-Info.plist

 <?xml version="1.0" encoding="UTF-8"?>
 <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
 <plist version="1.0">
 <dict>
         <key>CFBundleDevelopmentRegion</key>
         <string>English</string>
         <key>CFBundleDisplayName</key>
         <string>${PRODUCT_NAME}</string>
         <key>CFBundleExecutable</key>
         <string>${EXECUTABLE_NAME}</string>
         <key>CFBundleIconFile</key>
         <string></string>
         <key>CFBundleIdentifier</key>
-        <string>com.google.iOSShell</string>
+        <string>$(PRODUCT_BUNDLE_IDENTIFIER)</string>
         <key>CFBundleInfoDictionaryVersion</key>
         <string>6.0</string>
         <key>CFBundleName</key>
         <string>${PRODUCT_NAME}</string>
         <key>CFBundlePackageType</key>
         <string>APPL</string>
         <key>CFBundleSignature</key>
         <string>????</string>
         <key>CFBundleVersion</key>
         <string>1.0</string>
         <key>LSRequiresIPhoneOS</key>
         <true/>
         <key>NSMainNibFile</key>
         <string>MainWindow_iPhone</string>
         <key>NSMainNibFile~ipad</key>
         <string>MainWindow_iPad</string>
         <key>UISupportedInterfaceOrientations</key>
         <array>
                 <string>UIInterfaceOrientationPortrait</string>
         </array>
         <key>UISupportedInterfaceOrientations~ipad</key>
         <array>
                 <string>UIInterfaceOrientationPortrait</string>
                 <string>UIInterfaceOrientationPortraitUpsideDown</string>
                 <string>UIInterfaceOrientationLandscapeLeft</string>
                 <string>UIInterfaceOrientationLandscapeRight</string>
         </array>
 </dict>
 </plist>