Fix depricated File.exists?

Author: Igor Kapkov

ext/libv8/checkout.rb

@@ -36,7 +36,7 @@ def checkout!
     end
 
     def git?(dir)
-      File.exists?(File.join(dir, '.git'))
+      File.exist?(File.join(dir, '.git'))
     end
 
     def check_git_svn!

ext/libv8/location.rb

@@ -33,7 +33,7 @@ def configure(context = MkmfContext.new)
 
       def verify_installation!
         Libv8::Paths.object_paths.each do |p|
-          fail ArchiveNotFound, p unless File.exists? p
+          fail ArchiveNotFound, p unless File.exist? p
         end
       end
 

ext/libv8/paths.rb

@@ -19,7 +19,7 @@ def config
 
     def libv8_object(name)
       filename = "#{libv8_profile}/libv8_#{name}.#{config['LIBEXT']}"
-      unless File.exists? filename
+      unless File.exist? filename
         filename = "#{libv8_profile}/obj.target/tools/gyp/libv8_#{name}.#{config['LIBEXT']}"
       end
       return filename
@@ -28,7 +28,7 @@ def libv8_object(name)
     def libv8_profile
       base = "#{vendored_source_path}/out/#{Libv8::Arch.libv8_arch}"
       debug = "#{base}.debug"
-      File.exists?(debug) ? debug : "#{base}.release"
+      File.exist?(debug) ? debug : "#{base}.release"
     end
 
     def vendored_source_path