Required files
active_support
rubygems
active_record/base
active_record/observer
active_record/validations
active_record/callbacks
active_record/reflection
active_record/associations
active_record/aggregations
active_record/transactions
active_record/timestamp
active_record/acts/list
active_record/acts/tree
active_record/acts/nested_set
active_record/locking/optimistic
active_record/locking/pessimistic
active_record/migration
active_record/schema
active_record/calculations
active_record/xml_serialization
active_record/attribute_methods
active_record/connection_adapters/
active_record/query_cache
active_record/schema_dumper