GetUserFilter is adding the user to the request attribute so the user
who requested the URL is printed in the httpd_log but it is only
applied when running Gerrit with the embedded servlet container.
Move GetUserFilter from the gerrit-pgm to gerrit-httpd so it can be
applied when running Gerrit in a servlet container (e.g. Tomcat). Add
a parameter http.addUserAsRequestAttribute in gerrit config to
enable/disable this filter. It is enabled by default.
In tomcat, pattern %{User}r can be used in the AccessLog to print user
to get same functionality as httpd_log when running with the embedded
servlet container.
Change-Id: I591d594848a5b2d4aa9389965365e0621b39a51c
88e33ac9f1