Fix bug in create_installer.py namespace handling

The "namespace" itself should be considered as component name in case
of root component.

Change-Id: I0379a59942a4e792be157d1ff5a5d505c8582e8d
Reviewed-by: Johanna Äijälä <johanna.aijala@digia.com>
Reviewed-by: Simo Fält <simo.falt@digia.com>