improve doFilter() logging

[vladak]

I see entries like this in the Tomcat logs:

23-May-2017 23:09:42.081 INFO [http-nio-8888-exec-96] org.opensolaris.opengrok.web.AuthorizationFilter.doFilter access denied for uri: /source/xref/foo/

Ideally it should log the user identity.

Also, uri should be spelled in capital lettes.

[vladak]

while there, this line:

63              httpRes.sendError(403, "Access forbidden");

should be changed to use the symbolic instead of numeric error code.

[tulinkry]

user identity.

the problem is that we don't know what is the user identity