Do not calculate non essential info

There is no need to calculate a human readable date on the server side.
We supply the mtime and a client can easily convert that himself if
needed. This is already done most of the time since the date is often
not in the exact right format.

There is also no need to attach icon info. We have that available in
javascript. And else the client should get the right icon based on the
mimetype for its platform.

* Updated tests