908676 - make pulp-selinux conflict with pulp-selinux-server instead of ...

...obsoleting pulp-selinux-server

https://bugzilla.redhat.com/show_bug.cgi?id=908676

Since pulp-selinux-server is renamed to pulp-selinux, update to the latest version from the one in v1.0 is causing %preun steps when removing old pulp-selinux-server to execute and remove policies installed by new pulp-selinux. I tried to find a way around this but there is not easy way around it. Since migrate from v1.0 to v2.x anyway contains other manual steps, I have updated spec file such that we conflict pulp-selinux with pulp-selinux-server instead of obsoleting. If user has pulp-selinux installed, he will have to uninstall it when upgrading to 2.x.