Moved dependency setting from attributes to recipe.

In the attributes file the platform_family? "rhel" was evaluating to true on my hashicorp/precise64 Ubuntu box, causing this error :

==> default: [2014-06-25T10:15:56+00:00] FATAL: Chef::Exceptions::Package: package[python-devel] (vim::source line 24) had an error: Chef::Exceptions::Package: No version specified, and no candidate version available for python-devel
Switched package from ctags to exuberant-tags.

It was throwing this error :

==> default: [2014-06-25T10:21:15+00:00] FATAL: Chef::Exceptions::Package: package[ctags] (vim::source line 30) had an error: Chef::Exceptions::Package: ctags is a virtual package provided by 2 packages, you must explicitly select one to install