Compatibility with 2.7+

Moodle 2.7 officially deprecated the use of $module in mod/*/version.php files.
Replaced legacy logging with new Event API
Corrected a few EN language strings
Merge pull request #48 from skelty-unikent/feature/2.7_compat

Compatibility with 2.7+
Dropped support for Moodle < 2.7
Merge branch 'master' of github.com:unikent/moodle-mod_choicegroup

Conflicts:
	version.php