drag and drop: fails with paths containing spaces

Drag and drop fails when path contains spaces (latest GNU/Linux GNOME client / LRC / daemon master).

How to reproduce:

1. Create/Rename a file so that its path contains one or more spaces
2. Try to drag & drop it in the chatview
3. Nothing happens (expected: file transfer is initialized)

Logs:

• GNOME client / LRC

DataTransferModel::sendFile(), error

• daemon

[1530299596.914|27598|p2p.cpp           :780  ] 0x62300000e110[CNX] aborted, no devices for a54f6250337f27f369af896fd5bbd13d80f2fe44
[1530299599.414|27598|data_transfer.cpp :689  ] [XFER] invalid filename '/home/hlefeuvre/Downloads/TEST%20STUFF/poultry-farm-chicken-500x500.jpg'