Author: Simey Lameze
MDL-55121 environment: check for unsuported php version 7.1
http://git.moodle.org/gw?p=moodle.git;a=commit;h=5ed79a453a19f8150be8027e79cfa4f493ab3323
http://github.com/moodle/moodle/commit/5ed79a453a19f8150be8027e79cfa4f493ab3323
+ 3.1 en [unsupportedphpversion71,core_admin]