Do not send Content-Length headers with a value larger than PHP_INT_MAX
(2147483647) on Apache PHP SAPI 32-bit. PHP will eat them and send 2147483647
instead.
When X-Sendfile is enabled, Apache will send a correct Content-Length header,
even for files larger than 2147483647 bytes. When X-Sendfile is not enabled,
ownCloud will not send a Content-Length header. This prevents progress bars
from working, but allows the actual transfer to work properly.
Added new OC\Response API called setContentDispositionHeader() that
contains the needed workarounds for UTF8 and IE.
Refactored download code to use the new API.
Removed unused trashbin download file.