Merge pull request #1928 from chronize/master

fix fatal error when renaming new group with no users
check err
group null and err check
closes #1912
closes #1913
#1914
#1930

simple solution for now, wraps images with <a> that opens in new tab
Merge master
Merge branch 'master' of https://github.com/NodeBB/NodeBB

Conflicts:
	src/groups.js
optimize ACP groups screen, jQuery caching