Remove duplicated code for staging repository management

in org.fusesource.ide.camel.model.service.core.util.CamelMavenUtils.getAdditionalRepos() there is some duplicated code, it would be better to use something like org.fusesource.ide.projecttemplates.preferences.initializer.StagingRepositoriesPreferenceInitializer.getStagingRepositoriesAsList(String)