started work on #2082
Merge branch '0.5.1' into csrf-excision
latest translations and fallbacks

Conflicts:
	public/language/de/user.json
	public/language/nl/user.json
	public/language/pl/user.json
	public/language/sv/user.json
	public/language/vi/user.json
	public/language/zh_CN/user.json
Merge branch '0.5.1' into csrf-excision
closes https://github.com/NodeBB/NodeBB/issues/2101
closes https://github.com/NodeBB/NodeBB/issues/2104
closes https://github.com/NodeBB/NodeBB/issues/2103
fixed all POST routes to use new csrf middleware
Merge branch 'csrf-excision' into hashtalk
Merge branch 'hashtalk' of github.com:NodeBB/NodeBB into hashtalk
renamed middleware to applyCSRF, re: #2082
closes #2052
updated modules translations
show recent posts of child categories
duh
closes #2073
posts.getPostsByTid and posts.getPostsByPids now require a uid passed in
filter:post.getPosts now passes in uid
closes #2071
fixing groups.leave