Author: Dani Palou
MDL-51935 wiki: Add missing strings in wiki
http://git.moodle.org/gw?p=moodle.git;a=commit;h=5d2e3c1b977670e8b2c86c59414217977e82d041
http://github.com/moodle/moodle/commit/5d2e3c1b977670e8b2c86c59414217977e82d041
+ 2.8 en [cannotcomparenewerversion,mod_wiki]
+ 2.8 en [incorrectpageid,mod_wiki]
+ 2.8 en [incorrectsubwikiid,mod_wiki]
+ 2.8 en [incorrectwikiid,mod_wiki]