976568 - change yum version requirement to work on RHEL 6.4.

https://bugzilla.redhat.com/show_bug.cgi?id=976568

I tested createrepo 0.9.9-21 on RHEL 6.4 (which normally has 0.9.9-17) and both createrepo and modifyrepo seem to work okay with yum 3.2.29-40 (instead of 3.4.3-4).  The changelog does not suggest a change that requires yum 3.4.3-4.  Thinking the solution might be to update the Requires: in our deps/createrepo to require yum 3.2.29-40 and run with that.  

I created a repo, modified it with a comps.xml and installed a package from the created and modified repo and installed a package using group install and yum seemed happy.