* cookie users that load urls with the pattern /$cookie_url_base/user_id/redirect_url and redirect them to redirect_url
* implemented a local get_current_user_id() function to return either the id of an authenticated user or the id of the cookied user

see https://github.com/GigaOM/legacy-pro/issues/3168
coding standard fixes (spacing and comments only)
* code review responses: moved more bStat identity cookie-related constants into the config file or instance vars
* also hook to set_auth_cookie action to set the bStat identity cookie when the user signs in
fixed spacing
added PHPDOC comments for set_identity_cookie()
Merge pull request #7 from wluo/github-3168

url endpoint to track unauthenticated users before redirecting to final url