piwik/piwik — pull request #6169 by mattab (2014-09-09 06:31:17+00:00)
Title: User ID implementation 

This pull requests contains the implementation for User ID feature including Tracker API, JS and PHP Clients, new segment `userId`, displayed in Visitor Log and Visitor Profile, tests, and a new `nb_users` metric displayed in most APIs outputs.

Refs #6109 #3490 #6162