Build updates for Fedora 21.

This adds fc21 and removes fc19 from the 2.6 build. There are also two small
specfile fixes.
This line disappeared and I am not sure why. I assume it was from a merge but I couldn't find the removal in the git log.

The pulp 2.6 alpha 1 rpm had it:
```bash
$ rpm -qpl pulp-admin-client-2.6.0-0.1.alpha.el6.noarch.rpm | grep man1
/usr/share/man/man1/pulp-admin.1.gz
```

and if I look at the alpha 1 spec file, it's in there as well:

```
$ rpm2cpio pulp-2.6.0-0.1.alpha.el6.src.rpm | cpio -i --quiet --to-stdout pulp.spec  | grep -B11 "man1/pulp-admin.1"
%files admin-client
%defattr(-,root,root,-)
%{python_sitelib}/%{name}/client/admin/
%{python_sitelib}/pulp_client_admin*.egg-info
%dir %{_sysconfdir}/%{name}/admin
%dir %{_sysconfdir}/%{name}/admin/conf.d
%{_sysconfdir}/bash_completion.d/pulp-admin
%dir %{_usr}/lib/%{name}/admin/extensions/
%config(noreplace) %{_sysconfdir}/%{name}/admin/admin.conf
%{_bindir}/%{name}-admin
%doc README LICENSE COPYRIGHT
%doc %{_mandir}/man1/pulp-admin.1*
```