add Qiniu.fetch method

lib/qiniu.rb

@@ -118,6 +118,11 @@ module Qiniu
         code == StatusOK
       end
 
+      def fetch(bucket, target_url, key)
+        code, data = Storage.fetch(bucket, target_url, key)
+        code == StatusOK
+      end
+
       def batch(command, bucket, keys)
         code, data = Storage.batch(command, bucket, keys)
         code == StatusOK ? data : false

lib/qiniu/config.rb

@@ -20,6 +20,7 @@ module Qiniu
           :content_type    => 'application/x-www-form-urlencoded',
           :auth_url        => "https://acc.qbox.me/oauth2/token",
           :rs_host         => "http://rs.qiniu.com",
+          :fetch_host      => "http://iovip.qbox.me",
           :rsf_host        => "http://rsf.qbox.me",
           :up_host         => "http://up.qiniu.com",
           :pub_host        => "http://pu.qbox.me:10200",

lib/qiniu/management.rb

@@ -82,6 +82,11 @@ module Qiniu
           return HTTP.management_post(url)
         end # delete
 
+        def fetch(bucket, target_url, key)
+          url = Config.settings[:fetch_host] + '/fetch/' + Utils.urlsafe_base64_encode(target_url) + '/to/' + encode_entry_uri(bucket, key)
+          return HTTP.management_post(url)
+        end # fetch
+
         def batch(command, bucket, keys)
           execs = []
           keys.each do |key|