[INTERNAL] removed *magic* side effect from ResourceSelectionWizardPage

The pre-selection of resources where done in this class by invoking
static methods. This patch removes this calls and adds and option to
either preselect resources or none at all.

Change-Id: I511ba439219a6a3302a00cf32ccd67406433e7e4
Reviewed-on: http://saros-build.imp.fu-berlin.de/gerrit/1676
Tested-by: Jenkins CI
Reviewed-by: Stefan Rossbach <srossbach@arcor.de>