Fix Rakefile

Rakefile

@@ -43,8 +43,8 @@ namespace :build  do
   task :windows do
 
     # remove existing build folder
-    if (Dir.exists?("#{CMAKE_WINDOWS_BUILD_FOLDER})")
-      FileUtils.rm_rf("#{CMAKE_WINDOWS_BUILD_FOLDER})")
+    if Dir.exists?("#{CMAKE_WINDOWS_BUILD_FOLDER}")
+      FileUtils.rm_rf("#{CMAKE_WINDOWS_BUILD_FOLDER}")
     end
 
     # create build folder