Update gridstore_benchmark.rb to make it works with the current gem code.

bench/gridstore_benchmark

@@ -3,7 +3,6 @@ require 'rubygems'
 require 'mongo'
 
 include Mongo
-include GridFS
 
 db = Connection.new['benchmark-gridfs']
 sample_data = File.open(File.join(File.dirname(__FILE__), 'sample_file.pdf'), 'r').read
@@ -15,20 +14,22 @@ length = sample_data.length
 mb     = T * length / 1048576.0
 
 @grid = Grid.new(db)
+@grid_file_system = GridFileSystem.new(db)
+
 t1 = Time.now
 ids = []
 T.times do |n|
-  ids << @grid.put(sample_data, "mongodb-new-#{n}.pdf")
+  ids << @grid.put(sample_data, :filename => "mongodb-new-#{n}.pdf")
 end
 puts "Grid Write: #{mb / (Time.now - t1)} mb/s"
 
 t1 = Time.now
 T.times do |n|
-  GridStore.open(db, "mongodb.pdf-#{n}", 'w') do |f|
+  @grid_file_system.open("mongodb.pdf-#{n}", 'w') do |f|
     f.write(sample_data)
   end
 end
-puts "GridStore Write: #{mb / (Time.now - t1)} mb/s"
+puts "GridFileSystem Write: #{mb / (Time.now - t1)} mb/s"
 
 t1 = Time.now
 T.times do |n|
@@ -38,8 +39,8 @@ puts "Grid Read: #{mb / (Time.now - t1)} mb/s"
 
 t1 = Time.now
 T.times do |n|
-  old_data = GridStore.open(db, "mongodb.pdf-#{n}", 'r') do |f|
+  old_data = @grid_file_system.open("mongodb.pdf-#{n}", 'r') do |f|
     f.read
   end
 end
-puts "GridStore Read: #{mb / (Time.now - t1)} mb/s"
+puts "GridFileSystem Read: #{mb / (Time.now - t1)} mb/s"