Copy non-hashed js files to s3

We (@phamann and myself) would like to enable the copying of the non-hashed js files to s3 so that url references can remain unchanged in certain circumstances.

For now this is primarily so that a non hashed version of this formstack url can be generated;

https://assets-secure.guim.co.uk/javascripts/vendor/formstack-interactive-boot.03e0d0dfd005f551febc8caa63566ca4.js

cc @rich-nguyen