Required files
active_support
rubygems
active_record/base
active_record/observer
active_record/validations
active_record/callbacks
active_record/associations
active_record/aggregations
active_record/transactions
active_record/reflection
active_record/timestamp
active_record/acts/list
active_record/acts/tree
active_record/acts/nested_set
active_record/locking
active_record/migration
active_record/connection_adapters/mysql_adapter
active_record/connection_adapters/postgresql_adapter
active_record/connection_adapters/sqlite_adapter
active_record/connection_adapters/sqlserver_adapter
active_record/connection_adapters/db2_adapter
active_record/connection_adapters/oci_adapter
active_record/query_cache