Don't specifically use a non-standard format for ban times

git-svn-id: http://svn.gna.org/svn/wesnoth/trunk@56536 75b3775d-3801-0410-9e12-e2e43121521d
Add remaining time to ban information strings

git-svn-id: http://svn.gna.org/svn/wesnoth/trunk@56537 75b3775d-3801-0410-9e12-e2e43121521d