[Hack session] Create protected s3 endpoint for secured assets (faceb…

…ookresearch#311)

* Create s3 data script to fetch protected resources

* Change safety.txt load path

* Add fallback for s3 read with boto3 download using access tokens

* Fix bug in s3 download_file option

* Download protected resources in download script

* Add protected resources path to gitingore

* Update safety words unit test

* Add boto3 to requirements

* Format schema files and add OTHER and ALL to location and selector

* Fix NSP initialization in safety unit test

* Fix safety words loading bug

* Update unit test to check safety

* Fix merge conflict

* Remove safety check from datasets

* Correct gitignore paths

* Use pkg_resources to fetch resource location