The post install script does not work.

Hi,

I found that there is something wrong with the file omnibus/resources/rpm/spec.erb.

```erb
<% scripts.each do |script| -%>
%<%= File.basename(script) %>
<%= script %>
<% end -%>
```

The above code will just append the name of the post install script in place of <%= script %> and when you will try to install rpm then will give an error: NO such file or directory as it would look for the postinst script on your device which may be different than the one you used to build chef rpm.

So I think so that it should be like:

```erb
<% scripts.each do |script| -%>
%<%= File.basename(script) %>
<%= File.read(script) %>
<% end -%>
```

That shall copy the contents of  the post install script file after %post and then the installation would be successful.  

Is this an issue that needs to be fixed?