'source' resource attribute is incorrectly handled

[rcmorano]

Ohai!

I've been trying to use a full URI ('file:///' type in my case) as 'README.md' states, but found that the variable (IMHO) is not correctly parsed as it's type (cookbook_file / remote_file) is determined only by the length of the string/array is passed, so we reach the scenario where a single URI string can not be used as 'remote_file'.

I've workarounded it for my personal use, but I thought It would be nice to have it discussed/fixed starting from here :)

Bests!