Make the ServerManager add Servers to stuff.

Constructors shouldn't be leaking references to themselves all over
the place.

Change-Id: I4568a354e5dbd2561c247ff4b80badb781394662
Reviewed-on: http://gerrit.dmdirc.com/2808
Automatic-Compile: DMDirc Build Manager
Reviewed-by: Greg Holmes <greg@dmdirc.com>