PKGMGR_ACTION_AT_EXIT: change the default action to "summary"

- added combobox for changing the value
- see http://lists.opensuse.org/opensuse-factory/2013-11/msg00667.html
  for more details
- 3.1.4
Merge pull request #151 from yast/summary_dialog

PKGMGR_ACTION_AT_EXIT: change the default action to "summary"