Rpm

This is an implementation of RPM limited to null server (localhost) using rpmbuild. I plan to add mock virtual_server in a near feature which is a RPM tool generating cleaned and isolated chroot. I've added RPM spec too and a testing COPR repository has been created here: https://copr.fedorainfracloud.org/coprs/fepitre/reproducible-builds/. Please note that a bump in spec file will be required when tagging reprotest version 0.7.16.

@marmarek-guest @holger