Update fs_bucket.rb
Update fs_bucket.rb

Previously, this code was querying all IDs in the collection and storing them in an array. This is very inefficient and causes a long delay when inserting a file into fs.files, especially when the system is under a heavy load.
kay-kim/mongo-ruby-driver,aherlihy/mongo-ruby-driver,saghm/mongo-ruby-driver,jonhyman/mongo-ruby-driver,mongodb/mongo-ruby-driver,estolfo/mongo-ruby-driver,jonhyman/mongo-ruby-driver,kay-kim/mongo-ruby-driver,brandonblack/mongo-ruby-driver,estolfo/mongo-ruby-driver,mongodb/mongo-ruby-driver,saghm/mongo-ruby-driver,wandenberg/mongo-ruby-driver,mongodb/mongo-ruby-driver