enhanced permission handling

i think it should be possible to access the config-history if the user got the right to view configs in any way.
e.g. it is possible to allow a user to "READ" a config.xml so why not make the history accessible also. it would make it more easy to provide developers with information about changes to the build made on a productive system, without giving them full "CONFIGURE" access.
the original comments looked like this was the original idea anyway, so i hope it might be useful to someone else.

kind regards
christian