Fiddle with idea config.

- Stop it thinking "modules" is a valid module.
- Remove some paths that don't exist.
- Apply the auto-suggested gradle tweaks.
- Let it duplicate the VCS config lots, because it's quite insistent.

Change-Id: Ia8eb45562293fa6520e590e2bb1af3df470ce63d
Reviewed-on: http://gerrit.dmdirc.com/3914
Automatic-Compile: DMDirc Build Manager
Reviewed-by: Greg Holmes <greg@dmdirc.com>