Add Statsd Logging for Login Success/Failure

Add Statsd Logging for Login Success/Failure. Using the the nginx-statsd
module
https://github.com/zebrafishlabs/nginx-statsd
In case this gets to hacky, I'm curious if it makes sense to do the statsd tracking from lua in this case? Just did a quick search: https://github.com/stvp/lua-statsd-client