Add file reference to path object argument in rename function

__Why__
Having a reference to the original file can aid in determining what each particular file in a glob should be renamed to. For example, renaming a file based on a hash of its contents for cache busting.

__What I did__
I added a `file` property to the `path` object passed into the rename function. This property is not used to alter the file in any way -- it is only there for reference.