Added version constraint on yum cookbook to fix rhel/centos issues

Looks like the release of the 3.0 yum cookbook is what broke this for me.  The omnibus cookbook tries to include it and then has a rescue that hides the actual error message:

```
[2013-12-17T06:02:03+00:00] ERROR: could not find recipe epel for cookbook yum
Compiling Cookbooks...

================================================================================
Recipe Compile Error
================================================================================


Chef::Exceptions::RecipeNotFound
--------------------------------
could not find recipe epel for cookbook yum
```

If I remove the local changes to the Berksfile.lock - and manage to get Vagrant to run without modifying it, it works.  Otherwise it updates it to include 3.0 of yum and it breaks.