Replace _parse_yum function, add yum-utils dep for RPM

This commit fixes #4998 by getting rid of the parsing of yum output and replacing it with calls to repoquery. It also adds a dependency on yum-utils to the spec file. yum-utils is in RHEL/CentOS base but does not appear to be a default package (at least, not when installing CentOS from the minimal install ISO). Nevertheless, it requires no additional deps be packaged, so it is a painless addition to the spec file.