correct package name

Without this change, puppet seems to install this to
${MODULES_DIR}/yumrepos, which causes it to complain that the
wirbelsturm_yumrepo classes don't exist. Changing the name of the
module in this way resolves the issue.

I did get this working out of the box with vagrants, but when I
attempted to use the wirbelsturm repos on their own, I ran into this
issue. I'm not sure if it's a Puppet version issue, or if something in
the wirbelsturm spinup causes Puppet to load the yumrepo modules. I
was attempting to include the wirbelsturm_yumrepo::epel and most of
the other yum repos in my site.pp.