Added unauthenticated_user() output to the pyramid_exclog when extra_info key is true
The message that is used when extra_info key is set to true is wrapped
in dedent so the message is no longer indented.
The user name displayed in the message no longer shows up as None when
there is no user, it is now an empty string.
Added tests for checking that the user name is added to the message when
extra_info is set to True.
Documented adding the user in the message.
Added name to contributorsw:
Merge branch 'master' of https://github.com/brukhabtu/pyramid_exclog