We need to call action and care about SUMMARY_ONLY without calling ngcpcfg.
main_action will be used in push-parallel to call pull/build/apply actions
directly without calling ngcpcfg. Also 'ngcpcfg push' can be migrated on new
approach '--remote' (recommended by Guillem Jover, BTW, Tnx!) from the current
approach of executing commands through ngcp-ssh on remote host.
Change-Id: I927b8055a040f49d6cfb462a200ad4d4b2d660ff