Added Xcode native target to build OSX framework

xcode/mruby_fw/en.lproj/InfoPlist.strings

+/* Localized versions of Info.plist keys */
+

xcode/mruby_fw/mruby_fw-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>CFBundleExecutable</key>
+	<string>${EXECUTABLE_NAME}</string>
+	<key>CFBundleIconFile</key>
+	<string></string>
+	<key>CFBundleIdentifier</key>
+	<string>com.github.mruby.${PRODUCT_NAME:rfc1034identifier}</string>
+	<key>CFBundleInfoDictionaryVersion</key>
+	<string>6.0</string>
+	<key>CFBundleName</key>
+	<string>${PRODUCT_NAME}</string>
+	<key>CFBundlePackageType</key>
+	<string>FMWK</string>
+	<key>CFBundleShortVersionString</key>
+	<string>1.0</string>
+	<key>CFBundleSignature</key>
+	<string>????</string>
+	<key>CFBundleVersion</key>
+	<string>1</string>
+	<key>NSHumanReadableCopyright</key>
+	<string>Copyright © 2012 mruby Authors. All rights reserved.</string>
+	<key>NSPrincipalClass</key>
+	<string></string>
+</dict>
+</plist>

xcode/mruby_fw/mruby_fw-Prefix.pch

+//
+// Prefix header for all source files of the 'mruby_fw' target in the 'mruby_fw' project
+//
+
+#ifdef __OBJC__
+  #import <Cocoa/Cocoa.h>
+#endif