fix a bug in build system that app cannot be built with Ruby 2.1 when it would use UTF-8 as app name

http://hipbyte.myjetbrains.com/youtrack/issue/RM-370

lib/motion/project/builder.rb

@@ -495,7 +495,14 @@ EOS
     end
 
     def convert_filesystem_encoding(string)
-      eval `#{@nfd} "#{string}"`
+      if RUBY_VERSION < "2.1.0"
+        return eval `#{@nfd} "#{string}"`
+      else
+        # Dir.glob on Ruby 2.1 returns file path as "Normalization Form C".
+        # So, we do not convert to "Normalization Form D".
+        # (Ruby 2.0 or below, Dir.glob returns "Normalization Form D").
+        return string
+      end
     end
 
     def copy_resource(res_path, dest_path)