rcp: Fix error "Could not resolve module: org.eclipse.equinox.ds"

rcp: Fix error "Could not resolve module: org.eclipse.equinox.ds"

org.eclipse.equinox.event needs to be auto-started.
It was also necessary to tweak the start levels for this to work.
This was inspired by the platform's sdk.product file. See
http://git.eclipse.org/c/platform/eclipse.platform.releng.aggregator.git/tree/eclipse.platform.releng.tychoeclipsebuilder/sdk/sdk.product

Change-Id: Ie7e6cc7f5ba5d4fb35a7ae82d02d244bcfdba20e
Signed-off-by: Marc-Andre Laperle <marc-andre.laperle@ericsson.com>
Reviewed-on: https://git.eclipse.org/r/56457
Reviewed-by: Hudson CI
Reviewed-by: Bernd Hufmann <bernd.hufmann@ericsson.com>
Tested-by: Bernd Hufmann <bernd.hufmann@ericsson.com>