Author: Cameron Ball
MDL-21912 restore: Add admin setting to restore conflicting admin user
http://git.moodle.org/gw?p=moodle.git;a=commit;h=4a5fb82772aa4194788404323a8a65d4cd42e342
http://github.com/moodle/moodle/commit/4a5fb82772aa4194788404323a8a65d4cd42e342
+ 2.9 en [importgeneralduplicateadminallowed,core_backup]
+ 2.9 en [importgeneralduplicateadminallowed_desc,core_backup]
+ 2.9 en [restoremnethostidmismatch,core]