Some defensive programming

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Hard-code a couple more groupIds to help Fiji components build

Some Fiji projects still rely on properties for the groupIds of
certain components. Until the time this is fixed, let's bend over to
help poor Jarran Jenkins stay afloat.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>