Downloading renamed files

[Semir1212]

HH 1.15.3
Files 0.16.3

• Upload file
• Rename
• Download

--> Downloaded file has initial name

[yurabakhtin]

@luke- The problem was in browser caching, i.e. if url is not changed after previous downloading then browser downloads the file with same name from cache.
We already fixed similar issue after update a file content with adding url param hash_sha1 with value like 6d2c467f, but this param is not updated when file name is changed. This fix is from core side.
So I have decided to add a new param hash_name which 4 first chars of sha1(File->file_name), e.g. hash_name=ac1e and have done this only for this module because I think file name can be changed only by this module.
PR #204.