fixed: group members can answer questions
listen to the plugin settings that only experts can answer questions
when a user leave a group he loses the expert role for that group
remove the expert role if the user leaves the site
Merge branch 'master' of git@github.com:ColdTrick/elgg-questions
Merge branch 'master' of git@github.com:ColdTrick/elgg-questions

Conflicts:
	lib/events.php