Fix Bug 312492 - kmail freezes when trying to send a message from

dolphin

Be sure that we select files.
Otherwise it will try to add all home in attachement.
=> with this fix we will be sure that it's a file and will not freeze
all kde

For folder I will implement it in 4.11 we need to add a dialogbox to
confirm it etc.

FIXED-IN: 4.10