Also drop version.config to the build dir.

This allows tests not running against a jar to find the config
(and thus initialise IdentityManagers).

Change-Id: Ief27b9dfcb2451043f013a4aebba3ad51203ed4c
Reviewed-on: http://gerrit.dmdirc.com/4036
Reviewed-by: Greg Holmes <greg@dmdirc.com>
Automatic-Compile: DMDirc Build Manager