FileUploader first commit.

Collects files, renames them upon size and age constraints, tests the above.

Lots of ```TODO(dkorolev)```. And time to discuss export events in more detail.
Yes, I'm thinking same way now. Eventually it'll likely be a ```unique_ptr``` with a custom deleter, although I'm now thinking of wrapping something slightly more complex into this ```unique_ptr```, and perhaps even avoiding the whole ```unique_ptr``` thing by using move constructors.

On it, stay tuned. :)