RPM Support

When remote repository has directory structure e.g. RPM packages is in 'Packages' folder Pulp sync it well but after publish/distribution this repository primary.xml still has as location path 'Packages/pgk.rpm' but file itself is in root directory of PULPs' directory. It means that yum fail installation from this repository with '404 - Not Found'

Findings:

• at publish artifacts [0] here it is the base path of package
• at create metadata [1] it has full relative path of original repository root dir

Tested with CentOS7 repository [2]

[0] https://github.com/pulp/pulp_rpm/blob/master/pulp_rpm/app/tasks/publishing.py#L109 [1] https://github.com/pulp/pulp_rpm/blob/master/pulp_rpm/app/tasks/publishing.py#L259 [2] http://mirror.centos.org/centos/7.7.1908/os/x86_64/