follow up to issue #37 and spec file corrections to be more widely usable

As asked in https://github.com/darold/squidanalyzer/issues/37
* Setting group owner to root since squid group may not exist (and this ownership is not needed)
* Replace macros specific to initial contributor distro (%mkrel, %make, %makeinstall_std) by more standard commands
* add a BuildRoot macro (needed by RHEL). Note that the macro may be replaced by a distro specific one (Fedora does it)
*  add a "find | rm" to remove "perllocal.pod" and ".packlist" files which should not be packaged